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  • 1.
    Ahlberg, Charlotte
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Soderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    SELF-ORGANIZATION OF FIBERS IN A SUSPENSION BETWEEN TWO COUNTER-ROTATING DISCS2009Ingår i: PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER CONFERENCE, VOL 1, PTS A-C, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2009, s. 585-592Konferensbidrag (Refereegranskat)
    Abstract [en]

    The behavior of fibers suspended in a flow between two flat counter-rotating discs has been studied experimentally. Captured images of the fibers in the flow were analyzed by steerable filters, to extract positions and orientations of the fibers. Experiments were performed for gaps between the discs of less than one fiber length, and for equal absolute values of the angular velocities for the discs. The length-to-diameter ratio of the fibers was approximately 14. During certain conditions, the fibers organized themselves in a distinct manner, which we will denote as fiber trains, in which three or more fibers are aligned next to each other, at the same radial position, with a short fiber-to-fiber distance. The direction of the individual fibers is radial and the direction of the whole train is tangential. Trains containing more than 60 fibers have been observed and are quite impressing.

  • 2.
    Anderfors, Mikael
    et al.
    Innventia AB, Sweden.
    Llindström, Tom
    Innventia AB, Sweden.
    Söderberg, Daniel
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Innventia AB, Sweden.
    The use of microfibrillated cellulose in fine paper manufacturing: Results from a pilot scale papermaking trial2014Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, nr 3, s. 476-483Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work the strength enhancing capabilities of microfibrillated cellulose (MFC) in highly filled papers was studied. Both the MFC production and the paper making were done in pilot scale under realistic industrial conditions. The results clearly show that MFC (2.5 - 5.0wt-%) could improve the mechanical properties of highly filled papers (20 - 35 wt-% filler contents). All studied dry mechanical properties were improved and the improvements were most pronounced for Z-strength and fracture toughness. By combining the MFC with a C-starch dosage further improvements in mechanical properties could be achieved. The improvements in mechanical properties enabled increased filler content with retained properties. The filler increase could be achieved at the same time as the sheet formation and the dry content after pressing were improved.

  • 3. Ankerfors, M.
    et al.
    Lindström, T.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    The use of microfibrillated cellulose in high filler fine papers2013Ingår i: Pap. Conf. Trade Show, PaperCon, 2013, s. 1129-1132Konferensbidrag (Refereegranskat)
    Abstract [en]

    The field of communication, printing and writing papers has become an increasingly competitive field during the latest years as the market demand of printing and writing papers and newsprint has finally started to decline in the developed economies. One obvious approach to stay competitive is to increase the filler content of such papers. High filler paper is not a new idea and numerous approaches have been tested over the years to produce such papers. In order to reach industrial implementation, pilot-scale research and development under industrial conditions is necessary as a step after laboratory studies. Therefore an environment has been developed in order to perform projects targeting existing technologies for high filler applications as well as the new possibilities incurred by e.g. microfibrillated cellulose.

  • 4.
    Bellani, Gabriele
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Bach, Roland
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Experimental study of filtration of fiber suspensions: Part II: combined PIV and pressure drop measurements2011Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The filtration of a fiber suspension has been studied experimentally. Typical applications where pressure filtration occurs are: papermaking, air cleaners, production of composite materials, etc. In particular, in papermaking, the quality of the final product depends on the fiber orientation and mass distribution in the filtered material. Micro-variations of these properties can strongly affect the quality of the final product and they can occur during filtration, thus it is important to predict how this can happen. However, this is not an easy task, first because the filtered cake is a non-homogeneous compressible porous media, second because the filtration flow is non-stationary, since the cake is continuously evolving in time. Therefore in this work we focus on the filtration flow through formed steady fiber networks. For each grammage (i.e. mass of fibers per unit area), we simultaneously measure the pressure drop across the network and velocity field on top and below the fiber network using Particle Image Velocimetry (PIV). Compression of the fiber network can also be extracted from the PIV images. Normalized filtration resistance was found to be decreasing with increasing network thickness, as well as network compressibility. From the PIV data the influence of the formed fiber network on the flow field was analyzed and characteristic scales of the flow structures are quantified.

  • 5.
    Bellani, Gabriele
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Experimental study of filtration of fiber suspensions: Part I: fluid velocity and fluid-fiber interactionmeasurements2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A study of the flow in the direct vicinity of a forming wire and a fiber network during forming is reported. The measurements are performed with Particle Image Velocimetry in a scaled system. Index-of-refraction matching is used to gain optical access to the flow. Time resolved measurements of the flow velocity in the vertical and horizontal direction is obtained in a plane with a size of 60×40 fiber diameters. Data is obtained for three drainage velocities and two different lengths of the fibers. The relative level of the velocity fluctuationsis found to decrease with drainage velocity and is higher in the flow above a network mat of shorter fibers compared to the network made of longer fibers

  • 6.
    Bellani, Gabriele
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Experimental study of the forming process: Fluid velocity and fluid-fiber interaction measurements2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    A study of the flow in the direct vicinity of a forming wire and a fiber network during forming is reported. The measurements are performed with Particle Image Velocimetry in a scaled system. Index-of-refraction matching is used to gain optical access to the flow. Time resolved measurements of the flow velocity in the vertical and horizontal direction is obtained in a plane with a size of 60 × 40 fiber diameters. The spatial resolution is 2 fiber diameters. Data is obtained for three drainage velocities and two different lengths of the fibers. The relative level of the velocity fluctuations are found to decrease with drainage velocity and is higher in the flow above a network mat of shorter fibers compared to the network made of longer fibers. The size of the flow structures is obtained by spectral analysis and compared for the six cases.

  • 7.
    Brett, Calvin
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik.
    Mittal, Nitesh
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ohm, Wiebke
    DESY, Hamburg, Germany..
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik.
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. DESY, Hamburg, Germany..
    GISAS study of spray deposited metal precursor ink on a cellulose template2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 8.
    Brett, Calvin
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. DESY, Photon Sci, Hamburg, Germany.
    Mittal, Nitesh
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ohm, Wiebke
    DESY, Photon Sci, Hamburg, Germany..
    Söderberg, Daniel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik.
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. DESY, Photon Sci, Hamburg, Germany..
    In situ self-assembly study in bio-based thin films2018Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 9.
    Brouzet, Christophe
    et al.
    KTH.
    Mittal, Nitesh
    KTH.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers at the Nanoscale.Manuskript (preprint) (Övrigt vetenskapligt)
  • 10.
    Brouzet, Christophe
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Mittal, Nitesh
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers on the Nanoscale2019Ingår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, nr 6, s. 2286-2295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polydisperse fiber networks are the basis of many natural and manufactured structures, ranging from high-performance biobased materials to components of living cells and tissues. The formation and behavior of such networks are given by fiber properties such as length and stiffness as well as the number density and fiber-fiber interactions. Studies of fiber network behavior, such as connectivity or rigidity thresholds, typically assume monodisperse fiber lengths and isotropic fiber orientation distributions, specifically for nano scale fibers, where the methods providing time-resolved measurements are limited. Using birefringence measurements in a microfluidic flow-focusing channel combined with a flow stop procedure, we here propose a methodology allowing investigations of length-dependent rotational dynamics of nanoscale polydisperse fiber suspensions, including the effects of initial nonisotropic orientation distributions. Transition from rotational mobility to rigidity at entanglement thresholds is specifically addressed for a number of nanocellulose suspensions, which are used as model nanofiber systems. The results show that the proposed method allows the characterization of the subtle interplay between Brownian diffusion and nanoparticle alignment on network dynamics.

  • 11.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Håkansson, Karl
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Kvick, Mathias
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Evaluation of steerable filter for detection of fibres in flowing suspensions2011Ingår i: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 51, nr 4, s. 987-996Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Steerable filters are concluded to be useful in order to determine the orientation of fibers captured in digital images. The fiber orientation is a key variable in the study of flowing fiber suspensions. Here, digital image analysis based on a filter within the class of steerable filters is evaluated for suitability of finding the position and orientation of fibers suspended in flowing suspensions. In sharp images with small noise levels, the steerable filter succeeds in determining the orientation of artificially generated fibers with well-defined angles. The influence of reduced image quality on the orientation has been quantified. The effect of unsharpness and noise is studied and the results show that the error in orientation is less than 1° for moderate levels. Images from two flow cases, one laminar shear flow and one turbulent, are also analyzed. The fiber orientation distribution is determined in the flow-vorticity plane. For the laminar case a comparison is made to a robust, but computationally more expensive, method involving convolutions with an oriented elliptic filter. A good agreement is found when comparing the resulting fiber orientation distributions obtained with the two methods. For the turbulent case, it is demonstrated that correct results are obtained and that the method can handle overlapping fibers. 

  • 12.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Evaluation of steerable filters for detection of rod-like particles in flowing suspensionsManuskript (Övrigt vetenskapligt)
  • 13.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fibre orientation control related to papermaking2007Ingår i: Journal of Fluids Engineering - Trancactions of The ASME, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 129, nr 4, s. 457-465Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The orientation of fibers suspended in a shear flow flowing over a solid wall has been studied experimentally. The possibility to control this orientation with physical surface modifications, ridges, has also been studied. The fiber suspension was driven by gravity down a slightly inclined glass plate and a CCD-camera was used to capture images of the fibers in the flow. Image analysis based on the concept of steerable filters extracted the position and orientation of the fibers in the plane of the image. From these data, the velocity of the fibers was determined. When viewing the flow from the side, the velocity of the fibers at different heights was measured and found to agree with the theoretical solution for Newtonian flow down an inclined plate. Moving the camera so that the flow was filmed from below, the orientation and velocity of fibers in the plane parallel to the solid surface was determined. The known relationship between the velocity and the wall normal position of the fibers made it possible to determine the height above the plate for each identified fiber. Far away from the wall, the fibers were aligned with the flow direction in both cases. In a region close to the smooth plate surface the fibers oriented themselves perpendicular to the flow direction. This change in orientation did not occur when the surface structure was modified with ridges.

  • 14.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Orientation of fibres in a flowing suspension near a plane wallManuskript (Övrigt vetenskapligt)
  • 15.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Evaluation of a steerable filter for detection of fibres in flowing suspensionsManuskript (Övrigt vetenskapligt)
    Abstract [en]

    Steerable filters are concluded to be useful in order to determine the orientation of fibres captured in digital images. The fibre orientation is a key variable in the study of flowing fibre suspensions. Here digital image analysis based on a filter within the class of steerable filters is evaluated for suitability of finding the position and orientation of fibres suspended in flowing suspensions. In sharp images with small noise levels the steerable filter succeeds in determining the orientation of artificially generated fibres with well-defined angles. The influence of reduced image quality on the orientation has been quantified. The effect of unsharpness and noise is studied and the results show that the error in orientation is less than 1◦ for moderate levels. A set of images with fibres suspended in a shear flow is also analyzed. The fibre orientation distribution is determined in the flow-vorticity plane. In this analysis a comparison is also made to a robust, but computationally more expensive, method involving convolutions with an oriented elliptic filter. A good agreement is found when comparing the resulting fibre orientation distributions obtained with the two methods.

  • 16.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Orientation of slowly sedimenting fibers in a flowing suspensionnear a plane wall2007Ingår i: Svenska Mekanikdagarna, 2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    The effect of a wall on the orientation of slowly sedimenting fibers suspended in a shear flow has been studied experimentally. Experiments were performed at two concentrations with two aspect ratios, rp ≈ 7 and rp ≈ 30, where rp is defined as the fiber length divided by the diameter. For all cases the majority of the fibers were oriented close to parallel to the flow direction for distances farther away from the wall than half a fiber length. As the distance from the wall decreased a change in orientation was observed. At distances from the wall closer than about an eighth of a fiber length a significant amount of the fibers were oriented close to perpendicular to the flow. This was particularly clear for the shorter fibers. Due to the density difference between the fibers and the surrounding fluid the fiber concentration was increased in the near wall region. An increased concentration was found in a limited region close to half a fiber length from the wall. For the shorter fibers a large number of fibers was also detected in the very proximity of the wall.

  • 17.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fibre Orientation Control Related To Papermaking2006Ingår i: PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER CONFERENCE, VOL 1, PTS A AND B, 2006, s. 1501-1509Konferensbidrag (Refereegranskat)
    Abstract [en]

    The wall effect on the orientation of fibres suspended in a shear flow has been studied experimentally. A fibre suspension, driven by gravity down an inclined glass plate, constitutes the shear flow field. A CCD-camera was mounted underneath the flow in order to visualize the flow. The orientation of fibres in the plane perpendicular to the plate was determined, by using the concept of steerable filters. In a region close to the smooth plate surface the fibres oriented themselves perpendicular to the flow direction. This did not occur when the surface structure was modified with ridges.

  • 18.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. STFI-Packforsk AB, Sweden.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fibre orientation in the boundary layers of a planar converging channel2008Ingår i: TAPPI Press - Paper Conference and Trade Show, PaperCon '08, 2008, s. 384-408Konferensbidrag (Refereegranskat)
    Abstract [en]

    Experimental results on the fibre orientation in a laboratory scale headbox are reported. A steerable filter was used to determine the orientation of bleached and unbeaten birch fibres at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only low concentrations were studied. It is shown that the orientation varies with the distance from the wall. For most studied cases a more anisotropic profile was found closer to the wall.

  • 19.
    Carlsson, Allan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Fibre orientation near a wall of a headbox.2010Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, s. 204-212Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Experimental results on the fibre orientation in a laboratory scale headbox are reported. A steerable filter was used to determine the orientation of bleached unbeaten birch fibres at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only dilute suspensions were studied. It is shown that the fibre orientation distribution varies with the distance from the wall. Sufficiently far upstream in the headbox a more anisotropic distribution is found closer to the wall as compared to farther away from the wall.

  • 20.
    Fällman, Monika
    et al.
    KTH, Tidigare Institutioner                               , Mekanik.
    Lundell, Fredrik
    KTH, Tidigare Institutioner                               , Mekanik.
    Holm, Richard
    KTH, Tidigare Institutioner                               , Mekanik.
    Söderberg, L. Daniel
    STFI-Packforsk.
    A critical evaluation of ultrasound velocity profiling aiming towards measurements in fibre suspensionsManuskript (preprint) (Övrigt vetenskapligt)
  • 21.
    Gowda, Krishne, V
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Brouzet, Christophe
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Lefranc, Thibault
    Univ Claude Bernard, Univ Lyon, ENS Lyon, CNRS,Lab Phys, F-69342 Lyon, France..
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Effective interfacial tension in flow-focusing of colloidal dispersions: 3-D numerical simulations and experiments2019Ingår i: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 876, s. 1052-1076, artikel-id PII S0022112019005664Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An interface between two miscible fluids is transient, existing as a non-equilibrium state before complete molecular mixing is reached. However, during the existence of such an interface, which typically occurs at relatively short time scales, composition gradients at the boundary between the two liquids cause stresses effectively mimicking an interfacial tension. Here, we combine numerical modelling and experiments to study the influence of an effective interfacial tension between a colloidal fibre dispersion and its own solvent on the flow in a microfluidic system. In a flow-focusing channel, the dispersion is injected as core flow that is hydrodynamically focused by its solvent as sheath flows. This leads to the formation of a long fluid thread, which is characterized in three dimensions using optical coherence tomography and simulated using a volume of fluid method. The simulated flow and thread geometries very closely reproduce the experimental results in terms of thread topology and velocity flow fields. By varying the interfacial tension numerically, we show that it controls the thread development, which can be described by an effective capillary number. Furthermore, we demonstrate that the applied methodology provide the means to measure the ultra-low but dynamically highly significant effective interfacial tension.

  • 22.
    Holm, Richard
    et al.
    KTH, Tidigare Institutioner, Mekanik.
    Storey, S.
    Martinez, Mark
    Söderberg, L. Daniel
    KTH, Tidigare Institutioner, Mekanik.
    Visualization of streaming-like structures during settling of dilute and semi-dilute rigid fibre suspensions2004Ingår i: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666Artikel i tidskrift (Övrigt vetenskapligt)
  • 23.
    Holm, Richard
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, FaxénLaboratoriet. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    A theoretical analysis of the flow stability in roll forming of paper2005Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, nr 2, s. 212-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper deals with the fundamental mechanisms that control partial roll dewatering in papermaking. The flow around the forming cylinder is modelled in a cylindrical coordinate system and the wire is assumed to be impermeable. The governing equations are reduced based on a discussion where the magnitude of the different terms is estimated. Given this reduced set of equations a non-linear equation for the position of the wire is deduced. This clearly shows that one of the most important parameters is the Weber number, We, which is the non-dimensional number that can be obtained by comparing the effect of wire tension in relation to the momentum of the incoming headbox jet. The characteristics of the non-linear equation are discussed and the equation is linearized around the trivial solution to the equations, which gives that the wire is displaced a constant distance from the roll along the whole wrap. The linear equation has a standing wave solution with a specific wavelength that scales with We. This solution is compared to previously measured profiles regarding the wavelength of the waves.

  • 24.
    Holm, Richard
    et al.
    KTH, Tidigare Institutioner, Mekanik.
    Söderberg, L. Daniel
    STFI-Packforsk.
    Influence of shear on fibre orientation in the near wall region2004Artikel i tidskrift (Övrigt vetenskapligt)
  • 25.
    Holm, Richard
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, L. Daniel
    STFI-Packforsk.
    Shear influence on fibre orientation: Dilute suspension in the near wall region2007Ingår i: Rheologica Acta, ISSN 0035-4511, E-ISSN 1435-1528, Vol. 46, nr 5, s. 721-729Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this experimental work was to study the influence of shear close to a solid boundary on the fibre orientation in suspensions with different fibre aspect ratios and concentrations. We have studied a laminar suspension flow down an inclined plate. The fibre orientation in different wall parallel planes were measured. We applied an index-of-refraction (IR) matching method together with particle tracking techniques to obtain the fibre motion. The fibre orientation was extracted using a two-dimensional wavelet transform. The shear flow resulted in fibres perpendicularly oriented to the streamwise direction (rollers) in the near wall region. These rollers were observed in the experiment to perform a rolling-sliding motion down the inclined plate around a stable perpendicular orientation. As the distance to the wall increased the number of rollers decreased and the fibre orientation was unaffected from its initial streamwise orientation. As the aspect ratio increased the influence of shear on the fibre orientation decreased for all measured wall parallel planes. This was also the case for higher fibre concentrations. The purpose of this study was to contribute to the development of the capacity to control the sheet network structure in papermaking.

  • 26.
    Holm, Richard
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, FaxénLaboratoriet. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Norman, Bo
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Pappersteknologi.
    Experimental studies on dewatering during roll forming of paper2005Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, nr 2, s. 205-211Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pressure and wire position measurements have been performed in an experimental facility, the KTH-Former, which intends to model the roll-forming zone of a paper machine. The measured pressure distributions in the forming zone are shown to have more complex patterns than the simple model p=T/R, which normally is referred to as the nominal pressure. It is also shown that an increase in wire tension has a similar effect as a decrease in flow-rate on the shape of the pressure distribution. This is a consequence of that the flow to a large extent is governed by the relation between the dynamic pressure and the nominal pressure. For the case of partial dewatering the suction peak that appears at the roll-wire separation point has a strong influence on the pressure distribution upstream. Finally, it is shown that the drainage has a stabilizing effect on the dewatering pressure.

  • 27. Holmqvist, C.
    et al.
    Rosén, F.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    In-situ measurements of stock flow conditions in the twin-wire forming zone2018Ingår i: Paper Conference and Trade Show, PaperCon 2018, TAPPI Press , 2018, s. 59-72Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the present study, we report results from in-situ investigations of the forming process performed in the roll-blade section of a pilot machine. Direct measurements of the drainage pressure along the forming zone were obtained using a miniature fibre-optic pressure transducer inserted into the flow through the headbox jet. High-speed imaging of tracer particles using a transmitted light setup was performed to in an attempt to obtain direct measurements of the local stock speed. By replacing one section of a ceramic blade with a quartz glass piece, access was also obtained to the region on top of the blade. The combined picture that emerges from these measurements is that the pressure distribution and the velocity field along a twin-wire forming zone is significantly more complex than usually assumed, and that much remains to be understood about the dynamics of twin-wire forming.

  • 28.
    Håkansson, Karl
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fall, Andreas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Yu, Sun
    DESY, Hamburg Germany.
    Krywka, Christina
    Institute of experimental and applied physics. Kiel Germany.
    Roth, Stephan
    DESY, Hamburg Germany.
    Santoro, Gonzalo
    DESY, Hamburg Germany.
    Kvick, Mathias
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. Innventia AB, Stockholm Sweden.
    Hydrodynamic alignment and assembly of nanofibrils resulting in strong cellulose filaments2014Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, s. 4018-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanofibrils can be obtained from trees and have considerable potential as a building block for biobased materials. In order to achieve good properties of these materials, the nanostructure must be controlled. Here we present a process combining hydrodynamic alignment with a dispersion-gel transition that produces homogeneous and smooth filaments from a low-concentration dispersion of cellulose nanofibrils in water. The preferential fibril orientation along the filament direction can be controlled by the process parameters. The specific ultimate strength is considerably higher than previously reported filaments made of cellulose nanofibrils. The strength is even in line with the strongest cellulose pulp fibres extracted from wood with the same degree of fibril alignment. Successful nanoscale alignment before gelation demands a proper separation of the timescales involved. Somewhat surprisingly, the device must not be too small if this is to be achieved.

  • 29.
    Håkansson, Karl
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Kvick, Mathias
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Measurement of width and streakiness of particle streaks in turbulent flowsArtikel i tidskrift (Övrigt vetenskapligt)
  • 30.
    Håkansson, Karl
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fall, Andreas B.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Continuous assembly of aligned nanofibrils into a micro filamentManuskript (preprint) (Övrigt vetenskapligt)
  • 31.
    Håkansson, Karl
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Alignment of cellulose nanofibrils in a flow focusing device: mea-surements and calculations of flow and orientationManuskript (preprint) (Övrigt vetenskapligt)
  • 32.
    Håkansson, Karl
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Orientation of nano-fibrillated cellulose in accelerated flowManuskript (preprint) (Övrigt vetenskapligt)
  • 33.
    Håkansson, Karl M. O.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Kvick, Mathias
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Measurement of width and intensity of particle streaks in turbulent flows2013Ingår i: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 54, nr 6, s. 1555-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fibre streaks are observed in experiments with fibre suspensions in a turbulent half-channel flow. The preferential concentration methods, most commonly used to quantify preferential particle concentration, are in one dimension found to be concentration dependent. Two different new streak quantification methods are evaluated, one based on Voronoi analysis and the other based on artificial particles with an assigned fixed width. The width of the particle streaks and a measure of the intensity of the streaks, i.e. streakiness, are sought. Both methods are based on the auto-correlation of a signal, generated by summing images in the direction of the streaks. Common for both methods is a severe concentration dependency, verified in experiments keeping the flow conditions constant while the (very dilute) concentration of fibres is altered. The fixed width method is shown to be the most suitable method, being more robust and less computationally expensive. By assuming the concentration dependence to be related to random noise, an expression is derived, which is shown to make the streak width and the streakiness independent of the concentration even at as low concentrations as 0.05 particles per pixel column in an image. The streakiness is obtained by applying an artificial particle width equal to 20 % of the streak width. This artificial particle width is in this study found to be large enough to smoothen the correlation without altering the streakiness nor the streak width. It is concluded that in order to make quantitative comparisons between different experiments or simulations, the evaluation has to be performed with care and be very well documented.

  • 34.
    Håkansson, Karl M. O.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl-Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Nanofibril Alignment in Flow Focusing: Measurements and Calculations2016Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 120, nr 27, s. 6674-6686Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alignment of anisotropic supermolecular building blocks is crucial to control the properties of many novel materials. In this study, the alignment process of cellulose nanofibrils (CNFs) in a flow-focusing channel has been investigated using small-angle X-ray scattering (SAXS) and modeled using the Smoluchowski equation, which requires a known flow field as input. This flow field was investigated experimentally using microparticle-tracking velocimetry and by numerically applying the two-fluid level set method. A semidilute dispersion of CNFs was modeled as a continuous phase, with a higher viscosity as compared to that of water. Furthermore, implementation of the Smoluchowski equation also needed the rotational Brownian diffusion coefficient, which was experimentally determined in a shear viscosity measurement. The order of the nanofibrils was found to increase during extension in the flow-focusing channel, after which rotational diffusion acted on the orientation distribution, driving the orientation of the fibrils toward isotropy. The main features of the alignment and dealignment processes were well predicted by the numerical model, but the model overpredicted the alignment at higher rates of extension. The apparent rotational diffusion coefficient was seen to increase steeply as the degree of alignment increased. Thus, the combination of SAXS measurements and modeling provides the necessary framework for quantified studies of hydrodynamic alignment, followed by relaxation toward isotropy.

  • 35.
    Kamada, Ayaka
    et al.
    Univ Tokyo, Dept Bioengn, Tokyo, Japan..
    Mittal, Nitesh
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lendel, Christofer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Assembly mechanism of nanostructured whey protein filaments2016Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 252Artikel i tidskrift (Övrigt vetenskapligt)
  • 36.
    Kamada, Ayaka
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Mittal, Nitesh
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Ingverud, Tobias
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ohm, Wiebke
    Roth, Stephan V.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Photon Science, Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg, Germany.
    Lundell, Fredrik
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lendel, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Flow-assisted assembly of nanostructured protein microfibers2017Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, nr 6, s. 1232-1237Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Some of the most remarkable materials in nature are made from proteins. The properties of these materials are closely connected to the hierarchical assembly of the protein building blocks. In this perspective, amyloid-like protein nanofibrils (PNFs) have emerged as a promising foundation for the synthesis of novel bio-based materials for a variety of applications. Whereas recent advances have revealed the molecular structure of PNFs, the mechanisms associated with fibril-fibril interactions and their assembly into macroscale structures remain largely unexplored. Here, we show that whey PNFs can be assembled into microfibers using a flow-focusing approach and without the addition of plasticizers or cross-linkers. Microfocus small-angle X-ray scattering allows us to monitor the fibril orientation in the microchannel and compare the assembly processes of PNFs of distinct morphologies. We find that the strongest fiber is obtained with a sufficient balance between ordered nanostructure and fibril entanglement. The results provide insights in the behavior of protein nanostructures under laminar flow conditions and their assembly mechanism into hierarchical macroscopic structures.

  • 37.
    Karim, Zoheb
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    De-Castro, Daniele Oliveira
    KTH.
    Svedberg, A.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Wågberg, Lars
    KTH.
    Berglund, Lars
    KTH.
    Forming a cellulose based nanopaper using XPM2017Ingår i: International Conference on Nanotechnology for Renewable Materials 2017, TAPPI Press , 2017, s. 399-407Konferensbidrag (Refereegranskat)
  • 38. Krochak, P.
    et al.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Vomhoff, H.
    Faia, P.
    Monitoring tools for efficient papermaking2014Ingår i: Paper Conference and Trade Show, PaperCon 2014, TAPPI Press, 2014, s. 617-623Konferensbidrag (Refereegranskat)
    Abstract [en]

    With efficient papermaking, the objective is to produce a product that meets a sufficiently high performance standard at the lowest possible cost for production. Production costs tend to centre around the use of energy, raw fibre materials, and fresh water. Poor control of unit papermaking processes can create unwanted variability in product qualities. This forces producers to use excessive amounts of resource, including fibre raw material and energy in order to meet minimum product requirements. Control of unit processes is therefore an essential ingredient to efficient papermaking. One of the key challenges with process control is the ability to monitor accurately specific processes with a high spatial and temporal resolution in order to capture unwanted variability. New measurement methods have, within recent years, revealed surprisingly high levels of variability in many unit process, in product properties, and in the underlying structure of paper sheets. In particular, variability on the centimetre (or millisecond) scale is now understood to be significant. This work presents an overview of three novel measurement tools and their application for monitoring different stages of the paper production process. Specifically, the tools discussed here include, Electrical Impedance Tomography (EFT), STFI Online Forming Analyser (SOFA), and Infrared Thermography (IR) techniques. Potential implementations of each tool within different unit processes on a papermachine are supported by practical examples. When used together, it is shown that it could be possible to monitor the entire production line with enough accuracy for online control.

  • 39.
    Kvick, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Håkansson, Karl
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fibre orientation and fibre streaks in turbulent wall bounded flowManuskript (preprint) (Övrigt vetenskapligt)
  • 40.
    Kvick, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Effects of nano-fibrillated cellulose on curvature- and rotation-induced instabilities in channel flowManuskript (preprint) (Övrigt vetenskapligt)
  • 41.
    Kvick, Mathias
    et al.
    KTH. KTH Mech, Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden..
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH Mech, Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden..
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH Mech, Linne FLOW Ctr, S-10044 Stockholm, Sweden..
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. Innventia AB, S-11486 Stockholm, Sweden..
    Erratum to: Effect of fibrils on curvature-and rotation-induced hydrodynamic stability2015Ingår i: Acta Mechanica, ISSN 0001-5970, E-ISSN 1619-6937, Vol. 226, nr 4, s. 1319-1321Artikel i tidskrift (Refereegranskat)
  • 42.
    Kvick, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Stability of the flow in a flow-focusing deviceManuskript (preprint) (Övrigt vetenskapligt)
  • 43.
    Kvick, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Producing film from cellulose nanofibrils using a flow focusing deviceManuskript (preprint) (Övrigt vetenskapligt)
  • 44.
    Kvick, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Watanabe, K.
    Miyazaki, M.
    Matsubara, M.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fibre suspension flow in a plane channel: transition delay by cellolose nanofibrilsManuskript (preprint) (Övrigt vetenskapligt)
  • 45.
    Lundell, Fredrik
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Storey, Stefan
    Holm, Richard
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    THE EFFECT OF FIBRES ON LAMINAR-TURBULENT TRANSITION AND SCALES IN TURBULENT DECAY2005Ingår i: ADVANCES IN PAPER SCIENCE AND TECHNOLOGY: TRANSACTIONS OF THE 13TH FUNDAMENTAL RESEARCH SYMPOSIUM, VOLS 1-3 / [ed] IAnson SJ, BURY: PULP & PAPER FUNDAMENTAL RESEARCH SOCIETY , 2005, s. 19-34Konferensbidrag (Refereegranskat)
    Abstract [en]

    Two physical phenomena which determine fundamental possibilities of paper forming are studied. The two phenomena are (i) laminar/turbulent transition and (ii) decay of turbulence. At first, the relevance of the processes to paper making is reviewed and discussed. The state of the boundary layers (laminar or turbulent) on split vanes and the decay of turbulence in the free stream are found to be of uttermost importance for the control of layer purity, formation and other properties of the final paper. Experiments in which these two processes are studied by visualisations are presented. The experiments emphasize the impact of fibres on these processes, as compared to what is found with pure water. All experiments are performed in model experiments were the structures in the flow are visualised by the addition of small, flake-like particles. It is shown that the addition of fibres radically change the physics of the flow. In a water table experiment, the addition of fibres is seen to promote the production of turbulent spots. At high enough fibre concentrations, the flow of water and fibres is fully turbulent even if a flow of pure water is laminar. In decay of turbulence, the fibres are seen to radically change the energy transfer between different scales so that intermediate and small scales remain active for longer times. It is concluded that fibres have large effects on laminar-turbulent transition and turbulence decay and that improved knowledge of these effects are a corner stone in the understanding of head box flow and its relations to the resulting paper quality.

  • 46.
    Lundell, Fredrik
    et al.
    KTH, Skolan för teknikvetenskap (SCI).
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Alfredsson, P. Henrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Fluid Mechanics of Papermaking2011Ingår i: Annual Review of Fluid Mechanics, ISSN 0066-4189, E-ISSN 1545-4479, Vol. 43, s. 195-217Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Papermaking is to a large extent a multiphase flow process in which the structure of the material and many of the relevant properties of the final product are determined by the interaction between water and the wood fibers. The dominant feature of a suspension composed of wood fibers and water is its inherent propensity to form bundles of mechanically entangled fibers, known as fiber flocs. However, the phenomena apparent throughout the papermaking process are not unique but in fact have a generic fluid dynamical nature.

  • 47.
    MacKenzie, Jordan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Swerin, Agne
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. RISE Research Institutes of Sweden.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Turbulent stress measurements of fibre suspensions in a straight pipe2018Ingår i: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 30, nr 2, artikel-id 025104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The focus of the present work is an experimental study of the behaviour of semi-dilute, opaque fibre suspensions in fully developed cylindrical pipe flows. Measurements of the normal and turbulent shear stress components and the mean flow were acquired using phase-contrast magnetic resonance velocimetry. Two fibre types, namely, pulp fibre and nylon fibre, were considered in this work and are known to differ in elastic modulus. In total, three different mass concentrations and seven Reynolds numbers were tested to investigate the effects of fibre interactions during the transition from the plug flow to fully turbulent flow. It was found that in fully turbulent flows of nylon fibres, the normal, < u(z)u(z)>(+), and shear, < u(z)u(z)>(+) (note that <.> is the temporal average, u is the fluctuating velocity, z is the axial or streamwise component, and r is the radial direction), turbulent stresses increased with Reynolds number regardless of the crowding number (a concentration measure). For pulp fibre, the turbulent stresses increased with Reynolds number when a fibre plug was present in the flow and were spatially similar in magnitude when no fibre plug was present. Pressure spectra revealed that the stiff, nylon fibre reduced the energy in the inertial-subrange with an increasing Reynolds and crowding number, whereas the less stiff pulp fibre effectively cuts the energy cascade prematurely when the network was fully dispersed.

  • 48. Mair, C.
    et al.
    Lindström, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Control of the porous structure of paper in a continuous process2017Ingår i: International Conference on Nanotechnology for Renewable Materials 2017, TAPPI Press , 2017Konferensbidrag (Refereegranskat)
  • 49.
    Mittal, Nitesh
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ansari, Farhan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. Department of Materials Science and Engineering, Stanford University, Stanford, CA, United States.
    Gowda, Krishne, V
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Brouzet, Christophe
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Chen, Pan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. RISE Bioeconomy, P.O. Box 5604, Stockholm, SwedenRISE Bioeconomy, P.O. Box 5604, Stockholm, Sweden.
    Roth, Stephan Volkher
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Kotov, Nicholas Alexander
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Multiscale Control of Nanocellulose Assembly: Transferring Remarkable Nanoscale Fibril Mechanics to Macroscale Fibers2018Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, nr 7, s. 6378-6388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanoscale building blocks of many materials exhibit extraordinary mechanical properties due to their defect-free molecular structure. Translation of these high mechanical properties to macroscopic materials represents a difficult materials engineering challenge due to the necessity to organize these building blocks into multiscale patterns and mitigate defects emerging at larger scales. Cellulose nanofibrils (CNFs), the most abundant structural element in living systems, has impressively high strength and stiffness, but natural or artificial cellulose composites are 3-15 times weaker than the CNFs. Here, we report the flow-assisted organization of CNFs into macroscale fibers with nearly perfect unidirectional alignment. Efficient stress transfer from macroscale to individual CNF due to cross-linking and high degree of order enables their Young's modulus to reach up to 86 GPa and a tensile strength of 1.57 GPa, exceeding the mechanical properties of known natural or synthetic biopolymeric materials. The specific strength of our CNF fibers engineered at multiscale also exceeds that of metals, alloys, and glass fibers, enhancing the potential of sustainable lightweight high-performance materials with multiscale self-organization.

  • 50.
    Mittal, Nitesh
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för bioteknologi (BIO), Proteinteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Jansson, Ronnie
    KTH, Skolan för bioteknologi (BIO), Proteinteknologi.
    Widhe, Mona
    KTH, Skolan för bioteknologi (BIO), Proteinteknologi.
    Benselfelt, Tobias
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Innventia AB, Sweden.
    Håkansson, Karl M. O.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för bioteknologi (BIO), Proteinteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Hedhammar, My
    KTH, Skolan för bioteknologi (BIO), Proteinteknologi.
    Söderberg, Daniel
    KTH, Skolan för bioteknologi (BIO), Proteinteknologi. KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Ultrastrong and Bioactive Nanostructured Bio-Based Composites2017Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, nr 5, s. 5148-5159Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nature’s design of functional materials relies on smart combinations of simple components to achieve desired properties. Silk and cellulose are two clever examples from nature–spider silk being tough due to high extensibility, whereas cellulose possesses unparalleled strength and stiffness among natural materials. Unfortunately, silk proteins cannot be obtained in large quantities from spiders, and recombinant production processes are so far rather expensive. We have therefore combined small amounts of functionalized recombinant spider silk proteins with the most abundant structural component on Earth (cellulose nanofibrils (CNFs)) to fabricate isotropic as well as anisotropic hierarchical structures. Our approach for the fabrication of bio-based anisotropic fibers results in previously unreached but highly desirable mechanical performance with a stiffness of ∼55 GPa, strength at break of ∼1015 MPa, and toughness of ∼55 MJ m–3. We also show that addition of small amounts of silk fusion proteins to CNF results in materials with advanced biofunctionalities, which cannot be anticipated for the wood-based CNF alone. These findings suggest that bio-based materials provide abundant opportunities to design composites with high strength and functionalities and bring down our dependence on fossil-based resources.

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