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Yada, S., Bagheri, S., Hansson, J., Do-Quang, M., Lundell, F., van der Wijngaart, W. & Amberg, G. (2019). Droplet leaping governs microstructured surface wetting. Soft Matter, 15(46), 9528-9536
Open this publication in new window or tab >>Droplet leaping governs microstructured surface wetting
2019 (English)In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, no 46, p. 9528-9536Article in journal (Refereed) Published
Abstract [en]

Microstructured surfaces that control the direction of liquid transport are not only ubiquitous in nature, but they are also central to technological processes such as fog/water harvesting, oil–water separation, and surface lubrication. However, a fundamental understanding of the initial wetting dynamics of liquids spreading on such surfaces is lacking. Here, we show that three regimes govern microstructured surface wetting on short time scales: spread, stick, and contact line leaping. The latter involves establishing a new contact line downstream of the wetting front as the liquid leaps over specific sections of the solid surface. Experimental and numerical investigations reveal how different regimes emerge in different flow directions during wetting of periodic asymmetrically microstructured surfaces. These insights improve our understanding of rapid wetting in droplet impact, splashing, and wetting of vibrating surfaces and may contribute to advances in designing structured surfaces for the mentioned applications.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
droplet
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-263793 (URN)10.1039/C9SM01854A (DOI)000502539900011 ()31720679 (PubMedID)2-s2.0-85075748095 (Scopus ID)
Note

QC 20191126. QC 20200113

Available from: 2019-11-14 Created: 2019-11-14 Last updated: 2020-03-09Bibliographically approved
Shen, B., Liu, J., Shiomi, J., Amberg, G., Do-Quang, M., Kohno, M., . . . Takata, Y. (2018). Effect of dissolved gas on bubble growth on a biphilic surface: A diffuse-interface simulation approach. International Journal of Heat and Mass Transfer, 126, 816-829
Open this publication in new window or tab >>Effect of dissolved gas on bubble growth on a biphilic surface: A diffuse-interface simulation approach
2018 (English)In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 126, p. 816-829Article in journal (Refereed) Published
Abstract [en]

In this paper, we numerically study pool boiling of a binary (water and nitrogen) mixture on a surface endowed with a combination of hydrophobicity and hydrophilicity (i.e., the so called biphilic surface). Here we adopt a numerical approach based on the phase field theory, where the vapor-liquid interface is assumed to be of a finite thickness (hence diffusive in nature) and requires no explicit tracking schemes. The theoretical modeling of two-phase heat and mass transfer in water diluted with nitrogen demonstrates the signiant impact of impurities on bubble dynamics. The simulations show that locally high concentrations of nitrogen gas within the vapor bubble is essential to weakening the condensation effect, which results in sustained bubble growth and ultimately (partial) departure from the surface under the artificially enlarged gravity. Simply increasing the solubility of nitrogen in water, however, turns out to be counterproductive because possible re-dissolution of the aggregated nitrogen by the bulk water could deprive the bubble of vital gas contents, leading instead to continuous bubble shrinkage and collapse. Additionally, it is found that with the significant accumulation of nitrogen, the bubble interface is increasingly dominated by a strong interfacial thermocapillary flow due to the Marangoni effect.

Place, publisher, year, edition, pages
Pergamon Press, 2018
Keywords
Boiling, Bubble pinch-off, Binary mixture, Surface wettability, Diffuse-interface method
National Category
Water Engineering
Identifiers
urn:nbn:se:kth:diva-234556 (URN)10.1016/j.ijheatmasstransfer.2018.06.043 (DOI)000442972700069 ()2-s2.0-85048525356 (Scopus ID)
Note

QC 20180919

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-09-19Bibliographically approved
Nita, S., Do-Quang, M., Wang, J., Chen, Y.-C., Suzuki, Y., Amberg, G. & Shiomi, J. (2017). Electrostatic cloaking of surface structure for dynamic wetting. SCIENCE ADVANCES, 3(2), Article ID e1602202.
Open this publication in new window or tab >>Electrostatic cloaking of surface structure for dynamic wetting
2017 (English)In: SCIENCE ADVANCES, ISSN 2375-2548, Vol. 3, no 2, article id e1602202Article in journal (Refereed) Published
Abstract [en]

Dynamic wetting problems are fundamental to understanding the interaction between liquids and solids. Even in a superficially simple experimental situation, such as a droplet spreading over a dry surface, the result may depend not only on the liquid properties but also strongly on the substrate-surface properties; even for macroscopically smooth surfaces, the microscopic geometrical roughness can be important. In addition, because surfaces may often be naturally charged or electric fields are used to manipulate fluids, electric effects are crucial components that influence wetting phenomena. We investigate the interplay between electric forces and surface structures in dynamic wetting. Although surfacemicrostructures can significantly hinder spreading, we find that electrostatics can " cloak" themicrostructures, that is, deactivate the hindering. We identify the physics in terms of reduction in contact-line friction, which makes the dynamic wetting inertial force dominant and insensitive to the substrate properties.

Place, publisher, year, edition, pages
AMER ASSOC ADVANCEMENT SCIENCE, 2017
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-205150 (URN)10.1126/sciadv.1602202 (DOI)000397039500032 ()28275725 (PubMedID)2-s2.0-85041698410 (Scopus ID)
Note

QC 20170412

Available from: 2017-04-12 Created: 2017-04-12 Last updated: 2020-03-09Bibliographically approved
Weihong, Y., Do-Quang, M. & Amberg, G. (2017). Impact of viscoelastic droplets. Journal of Non-Newtonian Fluid Mechanics, 243, 38-46
Open this publication in new window or tab >>Impact of viscoelastic droplets
2017 (English)In: Journal of Non-Newtonian Fluid Mechanics, ISSN 0377-0257, E-ISSN 1873-2631, Vol. 243, p. 38-46Article in journal (Refereed) Published
Abstract [en]

We conduct numerical experiments on viscoelastic droplets hitting a flat solid surface. The results present time-resolved non-Newtonian stresses acting in the droplet. Comparing with the simulation of the impact of a Newtonian droplet, the effects of viscoelasticity on droplet behaviors such as splashing, the maximum spreading diameter and deformation are analyzed. With detailed information on the contact line region, we demonstrate how the contact line behaves according to the transition of the fluid property from elasticity dominated to shear-thinning dominated when a droplet expands and contracts on the substrate. The propose of this work is to discuss whether and how the elasticity in an impinging droplet takes effect.

Elsevier, 2017
Keywords
Contact line, Diffuse interface, Droplet impact, Dynamic wetting, Viscoelasticity, Drops, Elasticity, Non Newtonian flow, Shear thinning, Contact line regions, Contact lines, Droplet behaviors, Numerical experiments, Spreading diameters, Drop breakup
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-207327 (URN)10.1016/j.jnnfm.2017.03.003 (DOI)000401379500004 ()2-s2.0-85016417160 (Scopus ID)
Note

QC 20170608

Available from: 2017-06-08 Created: 2017-06-08 Last updated: 2017-11-10Bibliographically approved
Moradi Nour, Z., Do-Quang, M., Lundell, F. & Amberg, G. (2017). Interaction of sedimenting mass-ejecting particles. , 228
Open this publication in new window or tab >>Interaction of sedimenting mass-ejecting particles
2017 (English)Manuscript (preprint) (Other academic)
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-222609 (URN)
Funder
Swedish Research Council
Note

QC 20180212

Available from: 2018-02-12 Created: 2018-02-12 Last updated: 2018-02-12Bibliographically approved
Moradi Nour, Z., Amberg, G. & Do-Quang, M. (2017). Kinematics and dynamics of suspended gasifying particle. Acta Mechanica, 228(3), 1135-1151
Open this publication in new window or tab >>Kinematics and dynamics of suspended gasifying particle
2017 (English)In: Acta Mechanica, ISSN 0001-5970, E-ISSN 1619-6937, Vol. 228, no 3, p. 1135-1151Article in journal (Refereed) Published
Abstract [en]

The effect of gasification on the dynamics and kinematics of immersed spherical and non-spherical solid particles have been investigated using the three-dimensional lattice Boltzmann method. The gasification was performed by applying mass injection on particle surface for three cases: flow passing by a fixed sphere, rotating ellipsoid in simple shear flow, and a settling single sphere in a rectangular domain. In addition, we have compared the accuracy of employing two different fluid-solid interaction methods for the particle boundary. The validity of the gasification model was studied by comparing computed the mass flux from the simulation and the calculated value on the surface of the particle. The result was used to select a suitable boundary method in the simulations combined with gasification. Moreover, the reduction effect of the ejected mass flux on the drag coefficient of the fixed sphere have been validated against previous studies. In the case of rotating ellipsoid in simple shear flow with mass injection, a decrease on the rate of rotation was observed. The terminal (maximum) velocity of the settling sphere was increased by increasing the ratio of radial flux from the particle boundary.

Place, publisher, year, edition, pages
SPRINGER WIEN, 2017
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-205480 (URN)10.1007/s00707-016-1748-5 (DOI)000395107300021 ()2-s2.0-84995783715 (Scopus ID)
Note

QC 20170523

Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2018-02-12Bibliographically approved
Rosén, T., Kotsubo, Y., Aidun, C. K., Do-Quang, M. & Lundell, F. (2017). Orientational dynamics of a triaxial ellipsoid in simple shear flow: Influence of inertia. Physical review. E, 96(1), Article ID 013109.
Open this publication in new window or tab >>Orientational dynamics of a triaxial ellipsoid in simple shear flow: Influence of inertia
2017 (English)In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 96, no 1, article id 013109Article in journal (Refereed) Published
Abstract [en]

The motion of a single ellipsoidal particle in simple shear flow can provide valuable insights toward understanding suspension flows with nonspherical particles. Previously, extensive studies have been performed on the ellipsoidal particle with rotational symmetry, a so-called spheroid. The nearly prolate ellipsoid (one major and two minor axes of almost equal size) is known to perform quasiperiodic or even chaotic orbits in the absence of inertia. With small particle inertia, the particle is also known to drift toward this irregular motion. However, it is not previously understood what effects from fluid inertia could be, which is of highest importance for particles close to neutral buoyancy. Here, we find that fluid inertia is acting strongly to suppress the chaotic motion and only very weak fluid inertia is sufficient to stabilize a rotation around themiddle axis. Themechanism responsible for this transition is believed to be centrifugal forces acting on fluid, which is dragged along with the rotational motion of the particle. With moderate fluid inertia, it is found that nearly prolate triaxial particles behave similarly to the perfectly spheroidal particles. Finally, we also are able to provide predictions about the stable rotational states for the general triaxial ellipsoid in simple shear with weak inertia.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-211604 (URN)10.1103/PhysRevE.96.013109 (DOI)000405715200007 ()29347073 (PubMedID)2-s2.0-85026512840 (Scopus ID)
Funder
ÅForsk (Ångpanneföreningen's Foundation for Research and Development)
Note

QC 20170814

Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2020-03-09Bibliographically approved
Liu, J., Amberg, G. & Do-Quang, M. (2016). Diffuse interface method for a compressible binary fluid. Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 93(1), Article ID 013121.
Open this publication in new window or tab >>Diffuse interface method for a compressible binary fluid
2016 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 93, no 1, article id 013121Article in journal (Refereed) Published
Abstract [en]

Multicomponent, multiphase, compressible flows are very important in real life, as well as in scientific research, while their modeling is in an early stage. In this paper, we propose a diffuse interface model for compressible binary mixtures, based on the balance of mass, momentum, energy, and the second law of thermodynamics. We show both analytically and numerically that this model is able to describe the phase equilibrium for a real binary mixture (CO2 + ethanol is considered in this paper) very well by adjusting the parameter which measures the attraction force between molecules of the two components in the model. We also show that the calculated surface tension of the CO2 + ethanol mixture at different concentrations match measurements in the literature when the mixing capillary coefficient is taken to be the geometric mean of the capillary coefficient of each component. Three different cases of two droplets in a shear flow, with the same or different concentration, are simulated, showing that the higher concentration of CO2 the smaller the surface tension and the easier the drop deforms.

Place, publisher, year, edition, pages
American Physical Society, 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-182155 (URN)10.1103/PhysRevE.93.013121 (DOI)000368517500016 ()2-s2.0-84955590690 (Scopus ID)
Note

QC 20160218

Available from: 2016-02-18 Created: 2016-02-16 Last updated: 2017-11-30Bibliographically approved
Albernaz, D. L., Do-Quang, M., Hermanson, J. C. & Amberg, G. (2016). Droplet deformation and heat transfer in isotropic turbulence.
Open this publication in new window or tab >>Droplet deformation and heat transfer in isotropic turbulence
2016 (English)Manuscript (preprint) (Other academic)
Abstract [en]

The heat and mass transfer of deformable droplets in turbulent flows is crucial to a wide range of applications, such as cloud dynamics and internal combustion engines. This study investigates a droplet undergoing phase change in isotropic turbulence using numerical simulations with a hybrid lattice Boltzmann scheme. We solve the momentum and energy transport equations, where phase separation is controlled by a non-ideal equation of state and density contrast is taken into consideration. Deformation is caused by pressure and shear stress at the droplet interface. The statistics of thermodynamic variables is quantified and averaged in terms of the liquid and vapor phases. The occurrence of evaporation and condensation is correlated to temperature fluctuations, surface tension variation and turbulence intensity. The temporal spectra of droplet deformations are analyzed and related to the droplet surface area.Different modes of oscillation are clearly identified from the deformation power spectrum for low Taylor Reynolds number $Re_\lambda$, whereas nonlinearities are produced with the increase of $Re_\lambda$, as intermediate frequencies are seen to overlap. As an outcome a continuous spectrum is observed, which shows a decrease that scales as $\sim f^{-3}$.Correlations between the droplet Weber number, deformation parameter, fluctuations of the droplet volume and thermodynamic variables are also examined.

National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-183484 (URN)
Funder
Swedish Research Council, 2010-3938Swedish Research Council, 2011-5355
Note

QS 2016

Available from: 2016-03-14 Created: 2016-03-14 Last updated: 2016-03-14Bibliographically approved
Wang, Y., Gratadeix, A., Do-Quang, M. & Amberg, G. (2016). Events and conditions in droplet impact: a phase field prediction. International Journal of Multiphase Flow, 87, 54-65
Open this publication in new window or tab >>Events and conditions in droplet impact: a phase field prediction
2016 (English)In: International Journal of Multiphase Flow, ISSN 0301-9322, E-ISSN 1879-3533, Vol. 87, p. 54-65Article in journal (Refereed) Published
Abstract [en]

The phenomenon of droplet impact on a smooth, flat, partially wetted surface is studied by phase field simulation. A map of the different impact regimes is constructed for Reynolds numbers ranging from Re = 9 to Re = 9 x 10(4), and Ohnesorge numbers ranging from Oh = 3.3 x 10(-4) to Oh = 1.05. The results are compared with previous experiments from several aspects such as gas bubble entrapment, spreading radius and liquid sheet splashing, etc. The simulation proposes event predictions that are consistent with previous experiments. Our results and discussions give an overview of important characteristics during droplet impact, and provide insights on the droplet spreading after impact.

Elsevier, 2016
National Category
Physical Sciences
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-184142 (URN)10.1016/j.ijmultiphaseflow.2016.08.009 (DOI)000386645300006 ()2-s2.0-84987942203 (Scopus ID)
Note

QC 20191014

Available from: 2016-03-28 Created: 2016-03-28 Last updated: 2019-10-14Bibliographically approved
Identifiers
ORCID iD: orcid.org/0000-0003-2830-0454

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