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  • 1.
    Alizad Banaei, Arash
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Rahmani, Mona
    Univ British Columbia, Dept Math, Vancouver, BC V6T 1Z2, Canada..
    Martinez, D. Mark
    Univ British Columbia, Dept Chem & Biol Engn, Vancouver, BC V6T 1Z3, Canada..
    Brandt, Luca
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Inertial settling of flexible fiber suspensions2020In: Physical Review Fluids, E-ISSN 2469-990X, Vol. 5, no 2, article id 024301Article in journal (Refereed)
    Abstract [en]

    We study the inertial settling of suspensions of flexible and rigid fibers using an immersed boundary method. The fibers considered are inextensible and slender, with an aspect ratio of 20. For a single Galileo number of Ga = 160, we examine a range of dimensionless bending rigidities 0.1 < gamma < 20 and fiber concentrations 0.5 < nL(3) < 25, with n being the fiber number density and L the fiber length, that spans dilute and semidilute regimes. The settling fibers form streamers, regions where the fibers are packed and settle faster than the average settling velocity of the suspension, for nL(3) > 10. In the low-concentration regions outside the streamers, the fibers either go upward or have low settling velocities. Flexible fibers exhibit higher packing inside the streamers and smaller streamers compared to the streamers formed by the rigid fibers. Due to this higher packing, the flexible fibers settle faster compared to the rigid fibers. The formation of the streamers counterbalances the hindering of the settling velocity at higher concentrations. At higher nL(3), however, the maximum local concentration of fibers relative to a uniform distribution diminishes for both flexible and rigid fibers as the mobility of the fibers becomes limited due to the presence of other fibers in their vicinity. Due to this limited mobility, the deformation of the fibers and their settling orientation become insensitive to nL(3) for nL(3) > 7. In both the dilute and semidilute regimes, flexible fibers are more aligned with the direction perpendicular to gravity compared to rigid fibers.

  • 2.
    Banaei, Arash Alizad
    et al.
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Rosti, Marco E.
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Brandt, Luca
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Numerical study of filament suspensions at finite inertia2020In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 882, article id A5Article in journal (Refereed)
    Abstract [en]

    We present a numerical study on the rheology of semi-dilute and concentrated filament suspensions of different bending stiffness and Reynolds number, with the immersed boundary method used to couple the fluid and solid. The filaments are considered as one-dimensional inextensible slender bodies with fixed aspect ratio, obeying the Euler-Bernoulli beam equation. To understand the global suspension behaviour we relate it to the filament microstructure, deformation and elastic energy and examine the stress budget to quantify the effect of the elastic contribution. At fixed volume fraction, the viscosity of the suspension reduces when decreasing the bending rigidity and grows when increasing the Reynolds number. The change in the relative viscosity is stronger at finite inertia, although still in the laminar flow regime, as considered here. Moreover, we find the first normal stress difference to be positive as in polymeric fluids, and to increase with the Reynolds number; its value has a peak for an intermediate value of the filament bending stiffness. The peak value is found to be proportional to the Reynolds number, moving towards more rigid suspensions at larger inertia. Moreover, the viscosity increases when increasing the filament volume fraction, and the rate of increase of the filament stress with the bending rigidity is stronger at higher Reynolds numbers and reduces with the volume fraction. We show that this behaviour is associated with the formation of a more ordered structure in the flow, where filaments tend to be more aligned and move as a compact aggregate, thus reducing the filament-filament interactions despite their volume fraction increases.

  • 3. Benard, N.
    et al.
    Sujar Garrido, Patricia
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Bonnet, J. -P
    Moreau, E.
    Shear Layer and Shedding Modes Excitations of a Backward-Facing Step Flow by Surface Plasma Discharge2020In: Advances in Effective Flow Separation Control for Aircraft Drag Reduction, Springer, 2020, p. 55-74Chapter in book (Refereed)
    Abstract [en]

    The present experimental study interests in determining the influence of a linear plasma actuator (dielectric barrier discharge) on the development of a separated turbulent shear layer. More specifically, the plasma actuator is used to impose periodic perturbations at the step corner of a backward-facing step. Two different modes of excitation are explored. One concerns the shear layer mode of instability, a mode whose amplification leads to a minimization of the recirculation bubble. The present investigation shows how a dielectric barrier discharge plasma actuator can impose periodic perturbations that excite the shear layer mode and result in a strong regularization of the vortex street. The case of excitation at the shedding mode is also experimentally investigated using a DBD actuator. The measurements show the increase in Reynolds stress caused by this excitation as well as the specific growing mechanism of the shear layer. Indeed, phase-averaged flow measurements highlights the difference in the mechanism of development of the shear layer regarding the type of excitation used, the shear layer mode promoting a growing mechanism by fluid entrainment while the shedding mode enhancing the pairing of successive vortical flow structures.

  • 4.
    Canton, Jacopo
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Rinaldi, Enrico
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. Royal Inst Technol, Linne FLOW Ctr KTH Mech, SE-10044 Stockholm, Sweden..
    Örlü, Ramis
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Critical Point for Bifurcation Cascades and Featureless Turbulence2020In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 124, no 1, article id 014501Article in journal (Refereed)
    Abstract [en]

    In this Letter we show that a bifurcation cascade and fully sustained turbulence can share the phase space of a fluid flow system, resulting in the presence of competing stable attractors. We analyze the toroidal pipe flow, which undergoes subcritical transition to turbulence at low pipe curvatures (pipe-to-torus diameter ratio) and supercritical transition at high curvatures, as was previously documented. We unveil an additional step in the bifurcation cascade and provide evidence that, in a narrow range of intermediate curvatures, its dynamics competes with that of sustained turbulence emerging through subcritical transition mechanisms.

  • 5.
    Chaparian, Emad
    et al.
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Izbassarov, Daulet
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    De Vita, Francesco
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. Royal Inst Technol KTH, Mech Dept, SERC, Stockholm, Sweden..
    Brandt, Luca
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. Royal Inst Technol KTH, Mech Dept, SERC, Stockholm, Sweden..
    Tammisola, Outi
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Yield-stress fluids in porous media: a comparison of viscoplastic and elastoviscoplastic flows2020In: Meccanica (Milano. Print), ISSN 0025-6455, E-ISSN 1572-9648, Vol. 55, no 2, p. 331-342Article in journal (Refereed)
    Abstract [en]

    A numerical and theoretical study of yield-stress fluid flows in two types of model porous media is presented. We focus on viscoplastic and elastoviscoplastic flows to reveal some differences and similarities between these two classes of flows. Small elastic effects increase the pressure drop and also the size of unyielded regions in the flow which is the consequence of different stress solutions compare to viscoplastic flows. Yet, the velocity fields in the viscoplastic and elastoviscoplastic flows are comparable for small elastic effects. By increasing the yield stress, the difference in the pressure drops between the two classes of flows becomes smaller and smaller for both considered geometries. When the elastic effects increase, the elastoviscoplastic flow becomes time-dependent and some oscillations in the flow can be observed. Focusing on the regime of very large yield stress effects in the viscoplastic flow, we address in detail the interesting limit of 'flow/no flow': yield-stress fluids can resist small imposed pressure gradients and remain quiescent. The critical pressure gradient which should be exceeded to guarantee a continuous flow in the porous media will be reported. Finally, we propose a theoretical framework for studying the 'yield limit' in the porous media.

  • 6.
    Chauvat, Guillaume
    et al.
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI).
    Peplinski, Adam
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Henningson, Dan S.
    KTH, School of Engineering Sciences (SCI). KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Hanifi, Ardeshir
    KTH, School of Engineering Sciences (SCI). KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Global linear analysis of a jet in cross-flow at low velocity ratios2020In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 889, article id A12Article in journal (Refereed)
    Abstract [en]

    The stability of the jet in cross-flow is investigated using a complete set-up including the flow inside the pipe. First, direct simulations were performed to find the critical velocity ratio as a function of the Reynolds number, keeping the boundary-layer displacement thickness fixed. At all Reynolds numbers investigated, there exists a steady regime at low velocity ratios. As the velocity ratio is increased, a bifurcation to a limit cycle composed of hairpin vortices is observed. The critical bulk velocity ratio is found at approximately for the Reynolds number , above which a global mode of the system becomes unstable. An impulse response analysis was performed and characteristics of the generated wave packets were analysed, which confirmed results of our global mode analysis. In order to study the sensitivity of this flow, we performed transient growth computations and also computed the optimal periodic forcing and its response. Even well below this stability limit, at , large transient growth ( in energy amplification) is possible and the resolvent norm of the linearized Navier-Stokes operator peaks above . This is accompanied with an extreme sensitivity of the spectrum to numerical details, making the computation of a few tens of eigenvalues close to the limit of what can be achieved with double precision arithmetic. We demonstrate that including the meshing of the jet pipe in the simulations does not change qualitatively the dynamics of the flow when compared to the simple Dirichlet boundary condition representing the jet velocity profile. This is in agreement with the recent experimental results of Klotz et al. (J. Fluid Mech., vol. 863, 2019, pp. 386-406) and in contrast to previous studies of Cambonie & Aider (Phys. Fluids, vol. 26, 2014, 084101). Our simulations also show that a small amount of noise at subcritical velocity ratios may trigger the shedding of hairpin vortices.

  • 7.
    De Vita, Francesco
    et al.
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Rosti, Marco E.
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Caserta, Sergio
    Univ Naples Federico II, Dept Chem Mat & Ind Prod Engn, Piazzale V Tecchio 80, I-80125 Naples, Italy..
    Brandt, Luca
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    On the effect of coalescence on the rheology of emulsions2019In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 880, p. 969-991Article in journal (Refereed)
    Abstract [en]

    We present a numerical study of the rheology of a two-fluid emulsion in dilute and semidilute conditions. The analysis is performed for different capillary numbers, volume fractions and viscosity ratios under the assumption of negligible inertia and zero buoyancy force. The effective viscosity of the system increases for low values of the volume fraction and decreases for higher values, with a maximum for approximately 20% concentration of the disperse phase. When the dispersed fluid has lower viscosity, the normalised effective viscosity becomes smaller than 1 for high enough volume fractions. To single out the effect of droplet coalescence on the rheology of the emulsion we introduce an Eulerian force which prevents merging, effectively modelling the presence of surfactants in the system. When the coalescence is inhibited the effective viscosity is always greater than 1 and the curvature of the function representing the emulsion effective viscosity versus the volume fraction becomes positive, resembling the behaviour of suspensions of deformable particles. The reduction of the effective viscosity in the presence of coalescence is associated with the reduction of the total surface of the disperse phase when the droplets merge, which leads to a reduction of the interface tension contribution to the total shear stress. The probability density function of the flow topology parameter shows that the flow is mostly a shear flow in the matrix phase, with regions of extensional flow when the coalescence is prohibited. The flow in the disperse phase, instead, always shows rotational components. The first normal stress difference is positive, except for the smallest viscosity ratio considered, whereas the second normal difference is negative, with their ratio being constant with the volume fraction. Our results clearly show that the coalescence efficiency strongly affects the system rheology and that neglecting droplet merging can lead to erroneous predictions.

  • 8.
    Friederici, Anke
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Köpp, Wiebke
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Atzori, Marco
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Vinuesa, Ricardo
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Weinkauf, Tino
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Distributed Percolation Analysis for Turbulent Flows2019In: 2019 IEEE 9th Symposium on Large Data Analysis and Visualization, LDAV 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, p. 42-51, article id 8944383Conference paper (Refereed)
    Abstract [en]

    Percolation analysis is a valuable tool to study the statistical properties of turbulent flows. It is based on computing the percolation function for a derived scalar field, thereby quantifying the relative volume of the largest connected component in a superlevel set for a decreasing threshold. We propose a novel memory-distributed parallel algorithm to finely sample the percolation function. It is based on a parallel version of the union-find algorithm interleaved with a global synchronization step for each threshold sample. The efficiency of this algorithm stems from the fact that operations in-between threshold samples can be freely reordered, are mostly local and thus require no inter-process communication. Our algorithm is significantly faster than previous algorithms for this purpose, and is neither constrained by memory size nor number of compute nodes compared to the conceptually related algorithm for extracting augmented merge trees. This makes percolation analysis much more accessible in a large range of scenarios. We explore the scaling of our algorithm for different data sizes, number of samples and number of MPI processes. We demonstrate the utility of percolation analysis using large turbulent flow data sets.

  • 9. Karnama, A.
    et al.
    Haghighi, E. B.
    Vinuesa, Ricardo
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Organic data centers: A sustainable solution for computing facilities2019In: Results in Engineering, ISSN 2590-1230, Vol. 4, article id 100063Article in journal (Refereed)
    Abstract [en]

    In the present perspective article we provide an overview of on-going work in the literature and possible future development of organic data centers (ODC). These are defined as the combined operation of a data center and a greenhouse, and given their compatible thermal and operation requirements, ODCs have the potential to provide an excellent solution in terms of sustainability. In particular, we identify possible positive impacts of ODCs on at least 5 of the 17 United Nations (UN) Sustainable Development Goals (SDGs), including SDGs 2 and 13 on zero hunger and climate change, respectively.

  • 10.
    Le Clainche, S.
    et al.
    Univ Politecn Madrid, Sch Aerosp Engn, E-28040 Madrid, Spain..
    Izbassarov, Daulet
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Rosti, Marco E.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Brandt, Luca
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Tammisola, Outi
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Coherent structures in the turbulent channel flow of an elastoviscoplastic fluid2020In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 888, article id A5Article in journal (Refereed)
    Abstract [en]

    In this numerical and theoretical work, we study the turbulent channel flow of Newtonian and elastoviscoplastic fluids. The coherent structures in these flows are identified by means of higher order dynamic mode decomposition (HODMD), applied to a set of data non-equidistant in time, to reveal the role of the near-wall streaks and their breakdown, and the interplay between turbulent dynamics and non-Newtonian effects. HODMD identifies six different high-amplitude modes, which either describe the yielded flow or the yielded-unyielded flow interaction. The structure of the low- and high-frequency modes suggests that the interaction between high- and low-speed streamwise velocity structures is one of the mechanisms triggering the streak breakdown, dominant in Newtonian turbulence where we observe shorter near-wall streaks and a more chaotic dynamics. As the influence of elasticity and plasticity increases, the flow becomes more correlated in the streamwise direction, with long streaks disrupted for short times by localised perturbations, reflected in reduced drag. Finally, we present streamwise-periodic dynamic mode decomposition modes as a viable tool to describe the highly complex turbulent flows, and identify simple well-organised groups of travelling waves.

  • 11.
    Lupi, Valerio
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Canton, J.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    On the onset of transition in 90°-bend pipe flow2019In: 11th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2019, International Symposium on Turbulence and Shear Flow Phenomena, TSFP , 2019Conference paper (Refereed)
    Abstract [en]

    The present work deals with the global stability analysis of the flow in a 90◦-bend pipe with curvature δ = R/Rc = 0.3, being R the radius of the cross-section of the pipe and Rc the radius of curvature at the pipe centreline. Direct numerical simulations (DNS) for values of the bulk Reynolds number Reb = U-------D/v between 2000 and 3000 are performed. The bulk Reynolds number is based on the bulk velocity Ub, the pipe diameter D, and the kinematic viscosity ν. It is found that the flow is steady for Reb ≤ 2500, and two pairs of symmetric, counter-rotating vortices are observed in the section of the pipe downstream of the bend. Moreover, two recirculation regions are present inside the bend, one on the outer wall and the other on the inner one. For Reb ≥ 2550, the flow becomes periodic, oscillating with a fundamental non-dimensional frequency St = fD/Ub = 0.23. A global stability analysis reveals a pair of complex conjugate eigenvalues with positive real part. The velocity components of the unstable direct and adjoint eigenmodes are investigated, and it is observed that a large spatial separation occurs because of the non-normality of the linearised Navier–Stokes operator. Thus, an analysis of the structural sensitivity of the unstable eigenmode to spatially localised feedbacks is performed, in order to identify the core of the instability, the so-called wavemaker. It is found that the region located 15° downstream of the bend inlet, on the outer wall, is where the instability originates. Since flow separation is observed in this region, it is concluded that the instability is linked with the strong shear by the backflow phenomena.

  • 12.
    Mao, Huina
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    An inverse method for characterisation of the static elastic Hooke's tensors of solid frame of anisotropic open-cell materials2020In: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197, Vol. 147, article id 103198Article in journal (Refereed)
    Abstract [en]

    This paper proposes an inverse estimation method for the extraction of the equivalent, static elastic, Hooke's tensor. The inversion is based on a fitting of the displacements, obtained from a combination of static compression and shear traction loads, on the faces of a sample specimen. An equivalent, homogenised material model is found by varying the elastic moduli until a defined cost function, based on the error measured as the difference between the displacement fields, has reached a minimum, at which an anisotropic constitutive solid model has been identified. The method is built on a multi-level step-wise approach, both from a computational as well as an assumed constitutive model symmetry point of view. The principle of the method is validated for a target anisotropic solid material model. The proposed multi-level approach is developed and refined for a known open-cell structure based on the Kelvin cell geometry. The accuracy of the method is verified and various strategies for increasing the rate of convergence in the inversion are discussed.

  • 13.
    Mao, Huina
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Göransson, Peter
    KTH, Superseded Departments (pre-2005), Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    An inverse method for design and characterisation of acoustic materials2019Conference paper (Refereed)
    Abstract [en]

    This paper presents applications of an inverse method for the design and characterisation of anisotropic elastic material properties of acoustic porous materials. Full field 3D displacements under static surface loads are used as targets in the inverse estimation to fit a material model of an equivalent solid to the measurement data. Test cases of artificial open-cell foams are used, and the accuracy of the results are verified. The method is shown to be able to successfully characterise both isotropic and anisotropic elastic material properties. The paper demonstrates a way to reduce costs by characterising material properties based on the design model without a need for manufacturing and additional experimental tests.

  • 14.
    Mittal, Nitesh
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Fluid Physics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. Massachusetts Institute of Technology, Cambridge, MA 02142, United States.
    Benselfelt, Tobias
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Ansari, F.
    Gordeyeva, Korneliya
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Roth, Stephan Volkher
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. DESY, D-22607 Hamburg, Germany.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Ion-Specific Assembly of Strong, Tough, and Stiff Biofibers2019In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 58, no 51, p. 18562-18569Article in journal (Refereed)
    Abstract [en]

    Designing engineering materials with high stiffness and high toughness is challenging as stiff materials tend to be brittle. Many biological materials realize this objective through multiscale (i.e., atomic- to macroscale) mechanisms that are extremely difficult to replicate in synthetic materials. Inspired from the architecture of such biological structures, we here present flow-assisted organization and assembly of renewable native cellulose nanofibrils (CNFs), which yields highly anisotropic biofibers characterized by a unique combination of high strength (1010 MPa), high toughness (62 MJ m−3) and high stiffness (57 GPa). We observed that properties of the fibers are primarily governed by specific ion characteristics such as hydration enthalpy and polarizability. A fundamental facet of this study is thus to elucidate the role of specific anion binding following the Hofmeister series on the mechanical properties of wet fibrillar networks, and link this to the differences in properties of dry nanostructured fibers. This knowledge is useful for rational design of nanomaterials and is critical for validation of specific ion effect theories. The bioinspired assembly demonstrated here is relevant example for designing high-performance materials with absolute structural control.

  • 15.
    Picano, Francesco
    et al.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy.;Univ Padua, Ctr Studies & Activ Space CISAS, Via Venezia 1, I-35131 Padua, Italy..
    Tammisola, Outi
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Brandt, Luca
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Editorial2020In: Meccanica (Milano. Print), ISSN 0025-6455, E-ISSN 1572-9648, Vol. 55, no 2, p. 295-297Article in journal (Other academic)
  • 16.
    Rezaeiravesh, Saleh
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Vinuesa, Ricardo
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    A statistics toolbox for turbulent pipe flow in Nek50002019Report (Other academic)
  • 17.
    Rosti, Marco Edoardo
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Pramanik, Satyajit
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Brandt, Luca
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Mitra, Dhrubaditya
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, SE-10691 Stockholm, Sweden.
    The breakdown of Darcy's law in a soft porous material2020In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 16, no 4, p. 939-944Article in journal (Refereed)
    Abstract [en]

    We perform direct numerical simulations of the flow through a model of deformable porous medium. Our model is a two-dimensional hexagonal lattice, with defects, of soft elastic cylindrical pillars, with elastic shear modulus G, immersed in a liquid. We use a two-phase approach: the liquid phase is a viscous fluid and the solid phase is modeled as an incompressible viscoelastic material, whose complete nonlinear structural response is considered. We observe that the Darcy flux (q) is a nonlinear function - steeper than linear - of the pressure-difference (Delta P) across the medium. Furthermore, the flux is larger for a softer medium (smaller G). We construct a theory of this super-linear behavior by modelling the channels between the solid cylinders as elastic channels whose walls are made of material with a linear constitutive relation but can undergo large deformation. Our theory further predicts that the flow permeability is an universal function of Delta P/G, which is confirmed by the present simulations.

  • 18.
    Rumpler, Romain
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Rodrı́guez Sánchez, Raúl
    Chair of Structural Mechanics, Technical University of Munich.
    Göransson, Peter
    KTH, Superseded Departments (pre-2005), Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    MULTIVARIATE PADÉ APPROXIMANTS FOR FINITE ELEMENT SOLUTIONS WITH COMPLEX PARAMETRIC DEPENDENCE2019Conference paper (Refereed)
    Abstract [en]

    Most engineering applications involving solutions by numerical methods are dependent on several parameters, whose impact on the solution may significantly vary from one to the other. At times an evaluation of these multivariate solutions may be required at the expense of a prohibitively high computational cost. In the present work, a multivariate finite element approach is proposed, allowing for a fast evaluation of parametric responses. It is based on the construction of a reduced basis spanning a subspace able to capture rough variations of the response. The method consists in an extension of the Well-Conditioned Asymptotic Waveform Evaluation (WCAWE) to multivariate problems, by an appropriate choice of derivative sequences, and a selection of the most relevant basis components. It is validated and demonstrated for its potential on a semi-industrial sized 3D application involving coupled poroelasticand internal acoustic domains.

  • 19. Sanmiguel Vila, C.
    et al.
    Vinuesa, Ricardo
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Discetti, S.
    Ianiro, A.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Örlü, Ramis
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Experimental realisation of near-equilibrium adverse-pressure-gradient turbulent boundary layers2020In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 112, article id 109975Article in journal (Refereed)
    Abstract [en]

    A new experimental database of adverse-pressure-gradient (APG) turbulent boundary layers (TBLs) obtained through hot-wire anemometry and oil-film interferometry covering a momentum–loss Reynolds number 450&lt;Reθ&lt;23450 and Clauser pressure-gradient-parameter range up to β≈2.4 is presented. Both increasing and approximately constant β distributions with the same upstream history are characterised. Turbulence statistics are compared among the different pressure-gradient distributions with additional numerical and experimental zero-pressure-gradient (ZPG) TBL data. Cases at approximately constant β, which can be considered as canonical representations of the boundary layer under a certain pressure-gradient magnitude, exhibit skin-friction and shape-factor curves consistent with the ones proposed by Vinuesa et al. (2017). These curves show a similar scaling behaviour as those proposed by Nagib et al. (2007) for ZPG TBLs. The pre-multiplied power-spectral density is employed to study the differences in the large-scale energy content throughout the boundary layer. Two different large-scale phenomena are identified, the first one related to the pressure gradient and the second one (also present in high-Re ZPG TBLs) due to the Reynolds number. Recently proposed scaling laws by Kitsios et al. (2016) and Maciel et al. (2018) are tested over a wider Reynolds-number range and for different β cases. The mean velocity and streamwise velocity fluctuation profiles are found to be dependent on the upstream development. The mean velocity profile is found to be self-similar only in the outer region, in agreement with classical theory. The mean and higher-order statistics of the new APG TBL database are made available under www.flow.kth.se.

  • 20.
    Scapin, Nicolo
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Costa, Pedro
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. Univ Iceland, Fac Ind Engn Mech Engn & Comp Sci, Hjardarhagi 2-6, IS-107 Reykjavik, Iceland..
    Brandt, Luca
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KNorwegian Univ Sci & Technol NTNU, Dept Energy & Proc Engn, Trondheim, Norway..
    A volume-of-fluid method for interface-resolved simulations of phase-changing two-fluid flows2020In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 407, article id 109251Article in journal (Refereed)
    Abstract [en]

    We present a numerical method for interface-resolved simulations of evaporating two-fluid flows based on the volume-of-fluid (VoF) method. The method has been implemented in an efficient EFT-based two-fluid Navier-Stokes solver, using an algebraic VoF method for the interface representation, and extended with the transport equations of thermal energy and vaporized liquid mass for the single-component evaporating liquid in an inert gas. The conservation of vaporizing liquid and computation of the interfacial mass flux are performed with the aid of a reconstructed signed-distance field, which enables the use of well-established methods for phase change solvers based on level-set methods. The interface velocity is computed with a novel approach that ensures accurate mass conservation, by constructing a divergence-free extension of the liquid velocity field onto the entire domain. The resulting approach does not depend on the type of interface reconstruction (i.e. can be employed in both algebraic and geometrical VoF methods). We extensively verified and validated the overall method against several benchmark cases, and demonstrated its excellent mass conservation and good overall performance for simulating evaporating two-fluid flows in two and three dimensions.

  • 21.
    Sheng, Xia
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Yang, T.
    Timmer, Brian
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Willhammar, T.
    Cheung, O.
    Li, L.
    Brett, Calvin
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Zhang, Biaobiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Fan, Lizhou
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Guo, Yaxiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Zou, Xiaodong
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Hierarchical micro-reactor as electrodes for water splitting by metal rod tipped carbon nanocapsule self-assembly in carbonized wood2020In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 264, article id 118536Article in journal (Refereed)
    Abstract [en]

    Materials design of efficient electrochemical micro-reactors is challenging, although hierarchically structured, self-standing electrodes with catalyst arrays offer promise. Herein, catalyst function in compact micro-reactor electrodes is designed by nanostructural tailoring of carbonized wood for efficient water splitting. Specifically, NiFe rod tipped, N-doped graphitic carbon nanocapsule arrays are self-assembled in hierarchical wood, and the benefit of this unique presentation and its promotive effect on accessibility of the catalyst surfaces is apparent. This report also comprises the first wood based micro-reactor electrodes for electrocatalytic water oxidation demonstrating excellent performance. The overpotential for oxygen evolution reaction was as low as 180 mV for 10 mA cm−2 current density and TOFredox was high at a level of 5.8 s−1 (at 370 mV overpotential). This hierarchical electrode can also work as bifunctional catalyst (both as anodic and as cathodic electrode) for total water splitting with a cell potential of 1.49 V for 10 mA cm−2 in alkaline solution, suggestive of their potential also in other electrochemical applications.

  • 22.
    Tanarro, Alvaro
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Mallor, Fermin
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Offermans, Nicolas
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Peplinski, Adam
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Vinuesa, Ricardo
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Enabling adaptive mesh refinement for spectral-element simulations of turbulence around wing sectionsIn: Article in journal (Other academic)
    Abstract [en]

    The implementation of adaptive mesh refinement (AMR) in the spectral-element method code Nek5000 is used for the first time on the well-resolved large-eddy  simulation (LES) of the turbulent flow over wings. In particular, the flow over a NACA4412 profile with a 5° angle of attack at chord-based Reynolds number Rec=200,000 is analysed in the present work. The mesh, starting from a coarse resolution, is progressively refined by means of AMR, which allows for high resolution near the wall and wake whereas significantly larger elements are used in the far-field. The resulting mesh is of higher resolution than those in previous conformal cases, and it allows for the use of larger computational domains, avoiding the use of precursor RANS simulations to determine the boundary conditions. All of this with, approximately, 3 times lower total number of grid points if the same spanwise length is used. Turbulence statistics obtained in the AMR simulation show good agreement with the ones obtained with the conformal mesh. Finally, using AMR on wings will enable simulations at Rec beyond 1 million, thus allowing the study of pressure-gradient effects at high Reynolds numbers relevant for practical applications.

  • 23.
    Tanarro, Alvaro
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Vinuesa, Ricardo
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Effect of adverse pressure gradients on turbulent wing boundary layers2020In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 883, no A8, p. 1-28Article in journal (Refereed)
    Abstract [en]

        The characteristics of turbulent boundary layers (TBLs) subjected to adverse pressure gradients are analysed through well-resolved large-eddy simulations. The geometries under study are the NACA0012 and NACA4412 wing sections, at 0 and 5 degrees angle of attack, respectively, both of them at a Reynolds number based on inflow velocity and chord length Rec = 400,000. The turbulence statistics show that adverse pressure gradients (APGs) have a significant effect on the mean velocity, velocity fluctuations and turbulent kinetic energy budget, and this effect is more prominent on the outer region of the boundary layer. Furthermore, the effect of flow history is assessed by means of an integrated Clauser pressure-gradient parameter, β, through the study of cases with matching local values of β and the friction Reynolds number, Reτ, to isolate this effect. Our results show a noticeable effect of the flow history on the outer region, however the differences in the near-wall peak of the tangential velocity fluctuations appear to be mostly produced by the local APG magnitude. The one-dimensional power-spectral density shows energetic small scales in the outer region of APG TBLs, whereas these energetic scales do not appear in zero-pressure-gradient (ZPG) TBLs, suggesting that small scales near the wall are advected towards the outer layer by the APG. Moreover, the linear coherence spectra show that the spectral outer peak of high-Reynolds-number ZPG TBLs is highly correlated with the near-wall region , unlike APG TBLs which do not show such a correlation. This result, together with the different two-dimensional spectra of APG and high-Reynolds-number ZPG TBLs, suggests different energisation mechanisms due to APG and increase in Reynolds number. To the authors' knowledge, this is the first in-depth analysis of the TBL characteristics over wings, including detailed single-point statistics, spectra and coherence.

  • 24.
    Vinuesa, Ricardo
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Azizpour, Hossein
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Robotics, Perception and Learning, RPL.
    Leite, Iolanda
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Robotics, Perception and Learning, RPL.
    Balaam, Madeline
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Dignum, V.
    Domisch, S.
    Felländer, A.
    Langhans, S. D.
    Tegmark, M.
    Nerini, Francesco Fuso
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    The role of artificial intelligence in achieving the Sustainable Development Goals2020In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 11, no 1, article id 233Article, review/survey (Refereed)
    Abstract [en]

    The emergence of artificial intelligence (AI) and its progressively wider impact on many sectors requires an assessment of its effect on the achievement of the Sustainable Development Goals. Using a consensus-based expert elicitation process, we find that AI can enable the accomplishment of 134 targets across all the goals, but it may also inhibit 59 targets. However, current research foci overlook important aspects. The fast development of AI needs to be supported by the necessary regulatory insight and oversight for AI-based technologies to enable sustainable development. Failure to do so could result in gaps in transparency, safety, and ethical standards.

  • 25.
    Vinuesa, Ricardo
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Azizpour, Hossein
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Robotics, Perception and Learning, RPL.
    Leite, Iolanda
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Robotics, Perception and Learning, RPL.
    Balaam, Madeline
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Dignum, Virginia
    Umeå Univ, Responsible AI Grp, Dept Comp Sci, SE-90358 Umeå, Sweden..
    Domisch, Sami
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Muggelseedamm 310, D-12587 Berlin, Germany..
    Fellander, Anna
    AI Sustainabil Ctr, SE-11434 Stockholm, Sweden..
    Daniela Langhans, Simone
    BC3, Leioa 48940, Spain.;Univ Otago, Dept Zool, 340 Great King St, Dunedin 9016, New Zealand..
    Tegmark, Max
    MIT, Ctr Brains Minds & Machines, 77 Massachusetts Ave, Cambridge, MA 02139 USA..
    Nerini, Francesco Fuso
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis. KTH Royal Inst Technol, Unit Energy Syst Anal DESA, Brinellvagen 68, SE-1004 Stockholm, Sweden..
    The role of artificial intelligence in achieving the Sustainable Development Goals2020In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 11, no 1, article id 233Article, review/survey (Refereed)
    Abstract [en]

    The emergence of artificial intelligence (AI) and its progressively wider impact on many sectors requires an assessment of its effect on the achievement of the Sustainable Development Goals. Using a consensus-based expert elicitation process, we find that AI can enable the accomplishment of 134 targets across all the goals, but it may also inhibit 59 targets. However, current research foci overlook important aspects. The fast development of AI needs to be supported by the necessary regulatory insight and oversight for AI-based technologies to enable sustainable development. Failure to do so could result in gaps in transparency, safety, and ethical standards.

  • 26.
    Vinuesa, Ricardo
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Peplinski, Adam
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Atzori, Marco
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Fick, Lambert
    MCS Division, Argonne National Laboratory, 9700 Cass Ave., Lemont, Illinois 60439, USA.
    Marin, Oana
    MCS Division, Argonne National Laboratory, 9700 Cass Ave., Lemont, Illinois 60439, USA.
    Merzari, Elia
    MCS Division, Argonne National Laboratory, 9700 Cass Ave., Lemont, Illinois 60439, USA.
    Negi, Prabal
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Tanarro, Alvaro
    Schlatter, Philipp
    KTH, Superseded Departments (pre-2005), Mechanics. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Turbulence statistics in a spectral-element code: a toolbox for high-fidelity simulationsManuscript (preprint) (Other academic)
  • 27.
    Wei, Jianzheng
    et al.
    Harbin Inst Technol, Natl Key Lab Sci & Technol Composites Special Env, Harbin 150080, Peoples R China..
    Yu, Jianxin
    Harbin Inst Technol, Natl Key Lab Sci & Technol Composites Special Env, Harbin 150080, Peoples R China..
    Tan, Huifeng
    Harbin Inst Technol, Natl Key Lab Sci & Technol Composites Special Env, Harbin 150080, Peoples R China..
    Wang, Weizhi
    China Aerosp Sci & Technol Corp, Beijing Inst Space Mech & Elect, Beijing 100094, Peoples R China..
    Eriksson, Anders
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Structural Mechanics.
    Design and testing of inflatable gravity-gradient booms in space2020In: CEAS Space Journal, ISSN 1868-2502, E-ISSN 1868-2510, Vol. 12, no 1, p. 33-41Article in journal (Refereed)
    Abstract [en]

    Inflatable space structures have many advantages such as small size, high reliability, and low cost. Aiming at a gravity-gradient boom for an XY-1 satellite, New Technology Verifying Satellite-1, a slender inflatable boom with low magnetic is presented. First of all, an inflatable boom with six self-supporting thin shells made of carbon and Vectran fiber composite materials on the inner wall was designed for eliminating a magnetic dipole moment and increasing structural stiffness. A precise stowage was designed for a tip mass surrounded by a pair of lightweight honeycomb blocks added on the top of the boom. The stowed boom was tested by sine sweep vibrations with three directions on the ground to verify the reasonable design. The XY-1 satellite which carried the inflatable boom was launched into low orbit. After being stowed state in space for at least 6 months, the inflatable boom orderly unfolded a 2.0 kg tip mass to 3.0 m away in May, 2013. The inflatable boom was successfully deployed from a series of photographs received on the satellite. The results show that this kind of lightweight inflatable boom with self-supporting thin shells can orderly unfold and fulfil the function of gravity-gradient in space for a long time.

1 - 27 of 27
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