sh.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 29) Show all publications
Wang, Y., Minh, D.-Q. & Amberg, G. (2015). Dynamic wetting of viscoelastic droplets. Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 92(4), Article ID 043002.
Open this publication in new window or tab >>Dynamic wetting of viscoelastic droplets
2015 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 92, no 4, article id 043002Article in journal (Refereed) Published
Abstract [en]

We conduct numerical experiments on spreading of viscoelastic droplets on a flat surface. Our work considers a Giesekus fluid characterized by a shear-thinning viscosity and an Oldroyd-B fluid, which is close to a Boger fluid with constant viscosity. Our results qualitatively agree with experimental observations in that both shear thinning and elasticity enhances contact line motion, and that the contact line motion of the Boger fluid obeys the Tanner-Voinov-Hoffman relation. Excluding inertia, the spreading speed shows strong dependence on rheological properties, such as the viscosity ratio between the solvent and the polymer suspension, and the polymeric relaxation time. We also discuss how elasticity can affect contact line motion. The molecular migration theory proposed in the literature is not able to explain the agreement between our simulations and experimental results.

National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:sh:diva-30195 (URN)10.1103/PhysRevE.92.043002 (DOI)000362445200021 ()2-s2.0-84945179169 (Scopus ID)
Available from: 2015-11-09 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Albernaz, D., Do, Q. M. & Amberg, G. (2015). Multirelaxation-time lattice Boltzmann model for droplet heating and evaporation under forced convection. Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 91(4), Article ID 043012.
Open this publication in new window or tab >>Multirelaxation-time lattice Boltzmann model for droplet heating and evaporation under forced convection
2015 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 91, no 4, article id 043012Article in journal (Refereed) Published
Abstract [en]

We investigate the evaporation of a droplet surrounded by superheated vapor with relative motion between phases. The evaporating droplet is a challenging process, as one must take into account the transport of mass, momentum, and heat. Here a lattice Boltzmann method is employed where phase change is controlled by a nonideal equation of state. First, numerical simulations are compared to the D-2 law for a vaporizing static droplet and good agreement is observed. Results are then presented for a droplet in a Lagrangian frame under a superheated vapor flow. Evaporation is described in terms of the temperature difference between liquid-vapor and the inertial forces. The internal liquid circulation driven by surface-shear stresses due to convection enhances the evaporation rate. Numerical simulations demonstrate that for higher Reynolds numbers, the dynamics of vaporization flux can be significantly affected, which may cause an oscillatory behavior on the droplet evaporation. The droplet-wake interaction and local mass flux are discussed in detail.

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:sh:diva-30093 (URN)10.1103/PhysRevE.91.043012 (DOI)000353209300004 ()2-s2.0-84929118718 (Scopus ID)
Funder
Swedish Research Council, VR2010-3938]Swedish Research Council, VR2011-5355]Swedish National Infrastructure for Computing (SNIC)EU, FP7, Seventh Framework Programme, RI-312763]
Available from: 2015-08-07 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Liu, J., Do-Quang, M. & Amberg, G. (2015). Numerical Simulation of Rapid Expansion of Supercritical Carbon Dioxide. AIChE Journal, 61(1), 317-332
Open this publication in new window or tab >>Numerical Simulation of Rapid Expansion of Supercritical Carbon Dioxide
2015 (English)In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 61, no 1, p. 317-332Article in journal (Refereed) Published
Abstract [en]

Axisymmetric rapid expansion of supercritical carbon dioxide is investigated in this article. The extended generalized Bender equation of state is used to give a good description of the fluids over a wide range of pressure and temperature conditions. The locations of Mach disks are analyzed and compared with an experimental correlation for the case where there is no plate positioned in front of the nozzle exit. It is found that the disagreement between our numerical results and the experimental formula is very small when the pressure ratio is small, and increases as the pressure ratio increases. It is also found that with different equations of state, the predicted positions of Mach disks do not differ a lot, but the temperature profiles in the chamber differ a lot. The case where there is a plate positioned in front of the nozzle exit is also studied in this article. A universal similarity solution is obtained.

Keywords
rapid expansion, supercritical fluid, carbon dioxide, extended generalized Bender equation of state, Mach disk
National Category
Other Mechanical Engineering
Identifiers
urn:nbn:se:sh:diva-30152 (URN)10.1002/aic.14603 (DOI)000346598500028 ()2-s2.0-84920192433 (Scopus ID)
Funder
Swedish Research Council, 2011-5037]
Available from: 2015-01-29 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Wang, J., Do-Quang, M., Cannon, J. J., Yue, F., Suzuki, Y., Amberg, G. & Shiomi, J. (2015). Surface structure determines dynamic wetting. Scientific Reports, 5, Article ID 8474.
Open this publication in new window or tab >>Surface structure determines dynamic wetting
Show others...
2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 8474Article in journal (Refereed) Published
Abstract [en]

Liquid wetting of a surface is omnipresent in nature and the advance of micro-fabrication and assembly techniques in recent years offers increasing ability to control this phenomenon. Here, we identify how surface roughness influences the initial dynamic spreading of a partially wetting droplet by studying the spreading on a solid substrate patterned with microstructures just a few micrometers in size. We reveal that the roughness influence can be quantified in terms of a line friction coefficient for the energy dissipation rate at the contact line, and that this can be described in a simple formula in terms of the geometrical parameters of the roughness and the line-friction coefficient of the planar surface. We further identify a criterion to predict if the spreading will be controlled by this surface roughness or by liquid inertia. Our results point to the possibility of selectively controlling the wetting behavior by engineering the surface structure.

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:sh:diva-30191 (URN)10.1038/srep08474 (DOI)000349358700013 ()25683872 (PubMedID)2-s2.0-84923363599 (Scopus ID)
Funder
VINNOVA
Available from: 2015-03-24 Created: 2016-06-01 Last updated: 2017-07-17Bibliographically approved
Liu, J., Do-Quang, M. & Amberg, G. (2015). Thermohydrodynamics of boiling in binary compressible fluids. Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 92(4), Article ID 043017.
Open this publication in new window or tab >>Thermohydrodynamics of boiling in binary compressible fluids
2015 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 92, no 4, article id 043017Article in journal (Refereed) Published
Abstract [en]

We numerically study the thermohydrodynamics of boiling for a CO2 + ethanol mixture on lyophilic and lyophobic surfaces in both closed and open systems, based on a diffuse interface model for a two-component system. The corresponding wetting boundary conditions for an isothermal system are proposed and verified in this paper. New phenomena due to the addition of another component, mainly the preferential evaporation of the more volatile component, are observed. In the open system and the closed system, the physical process shows very different characteristics. In the open system, except for the movement of the contact line, the qualitative features are rather similar for lyophobic and lyophilic surfaces. In the closed system, the vortices that are observed on a lyophobic surface are not seen on a lyophilic surface. More sophisticated wetting boundary conditions for nonisothermal, two-component systems might need to be further developed, taking into account the variations of density, temperature, and surface tension near the wall, while numerical results show that the boundary conditions proposed here also work well even in boiling, where the temperature is nonuniform.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2015
Keywords
Lattice Boltzmann Simulation, Level Set Methods, Numerical-Simulation, Heat-Transfer, 2-Phase Flows, Bubble-Growth, Mixtures, Surface, Liquid, Volume
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Materials Engineering Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:sh:diva-30151 (URN)10.1103/PhysRevE.92.043017 (DOI)000363301500007 ()2-s2.0-84946761833 (Scopus ID)
Available from: 2015-12-11 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Ogden, S., Boden, R., Do-Quang, M., Wu, Z. G., Amberg, G. & Hjort, K. (2014). Fluid behavior of supercritical carbon dioxide with water in a double-Y-channel microfluidic chip. Microfluidics and Nanofluidics, 17(6), 1105-1112
Open this publication in new window or tab >>Fluid behavior of supercritical carbon dioxide with water in a double-Y-channel microfluidic chip
Show others...
2014 (English)In: Microfluidics and Nanofluidics, ISSN 1613-4982, E-ISSN 1613-4990, Vol. 17, no 6, p. 1105-1112Article in journal (Refereed) Published
Abstract [en]

The use of supercritical carbon dioxide (scCO(2)) as an apolar solvent has been known for decades. It offers a greener approach than, e.g., hexane or chloroform, when such solvents are needed. The use of scCO(2) in microsystems, however, has only recently started to attract attention. In microfluidics, the flow characteristics need to be known to be able to successfully design such components and systems. As supercritical fluids exhibit the exciting combination of low viscosity, high density, and high diffusion rates, the fluidic behavior is not directly transferrable from aqueous systems. In this paper, three flow regimes in the scCO(2)-liquid water two-phase microfluidic system have been mapped. The effect of both total flow rate and relative flow rate on the flow regime is evaluated. Furthermore, the droplet dynamics at the bifurcating exit channel are analyzed at different flow rates. Due to the low viscosity of scCO(2), segmented flows were observed even at fairly high flow rates. Furthermore, the carbon dioxide droplet behavior exhibited a clear dependence on both flow rate and droplet length.

Keywords
Two-phase flow, Segmented flow, Parallel flow, Wavy flow, Droplet dynamics
National Category
Nano Technology Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:sh:diva-30162 (URN)10.1007/s10404-014-1399-6 (DOI)000345389900014 ()2-s2.0-84912091166 (Scopus ID)
Available from: 2015-01-09 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Liu, J., Amberg, G. & Do-Quang, M. (2014). Numerical simulation of particle formation in the rapid expansion of supercritical solution process. Journal of Supercritical Fluids, 95, 572-587
Open this publication in new window or tab >>Numerical simulation of particle formation in the rapid expansion of supercritical solution process
2014 (English)In: Journal of Supercritical Fluids, ISSN 0896-8446, E-ISSN 1872-8162, Vol. 95, p. 572-587Article in journal (Refereed) Published
Abstract [en]

In this paper, we numerically study particle formation in the rapid expansion of supercritical solution (RESS) process in a two dimensional, axisymmetric geometry, for a benzoic acid + CO2 system. The fluid is described by the classical Navier-Stokes equation, with the thermodynamic pressure being replaced by a generalized pressure tensor. Homogenous particle nucleation, transport, condensation and coagulation are described by a general dynamic equation, which is solved using the method of moments. The results show that the maximal nucleation rate and number density occurs near the nozzle exit, and particle precipitation inside the nozzle might not be ignored. Particles grow mainly across the shocks. Fluid in the shear layer of the jet shows a relatively low temperature, high nucleation rate, and carries particles with small sizes. On the plate, particles within the jet have smaller average size and higher geometric mean, while particles outside the jet shows a larger average size and a lower geometric mean. Increasing the preexpansion temperature will increase both the average particle size and standard deviation. The preexpansion pressure does not show a monotonic dependency with the average particle size. Increasing the distance between the plate and the nozzle exit might decrease the particle size. For all the cases in this paper, the average particle size on the plate is on the order of tens of nanometers.

Keywords
Supercritical fluid, Rapid expansion, Particle formation, Method of moments, Nucleation, Condensation, Coagulation
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:sh:diva-30150 (URN)10.1016/j.supflu.2014.08.033 (DOI)000347360800068 ()2-s2.0-84916880859 (Scopus ID)
Funder
Swedish Research Council, 2011-5037]
Available from: 2015-02-05 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Do-Quang, M., Amberg, G., Brethouwer, G. & Johansson, A. V. (2014). Simulation of finite-size fibers in turbulent channel flows. Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 89(1), Article ID 013006.
Open this publication in new window or tab >>Simulation of finite-size fibers in turbulent channel flows
2014 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 89, no 1, article id 013006Article in journal (Refereed) Published
Abstract [en]

The dynamical behavior of almost neutrally buoyant finite-size rigid fibers or rods in turbulent channel flow is studied by direct numerical simulations. The time evolution of the fiber orientation and translational and rotational motions in a statistically steady channel flow is obtained for three different fiber lengths. The turbulent flow is modeled by an entropy lattice Boltzmann method, and the interaction between fibers and carrier fluid is modeled through an external boundary force method. Direct contact and lubrication force models for fiber-fiber interactions and fiber-wall interaction are taken into account to allow for a full four-way interaction. The density ratio is chosen to mimic cellulose fibers in water. It is shown that the finite size leads to fiber-turbulence interactions that are significantly different from earlier reported results for point like particles (e.g., elongated ellipsoids smaller than the Kolmogorov scale). An effect that becomes increasingly accentuated with fiber length is an accumulation in high-speed regions near the wall, resulting in a mean fiber velocity that is higher than the mean fluid velocity. The simulation results indicate that the finite-size fibers tend to stay in the high-speed streaks due to collisions with the wall. In the central region of the channel, long fibers tend to align in the spanwise direction. Closer to the wall the long fibers instead tend to toward to a rotation in the shear plane, while very close to the wall they become predominantly aligned in the streamwise direction.

Keywords
Lattice-Boltzmann Method, Ellipsoidal Particles, Shear-Flow, Numerical-Simulation, Drag Reduction, Viscous-Fluid, Orientation, Motion
National Category
Applied Mechanics
Identifiers
urn:nbn:se:sh:diva-30120 (URN)10.1103/PhysRevE.89.013006 (DOI)000332160600013 ()2-s2.0-84894594301 (Scopus ID)
Funder
Swedish Research Council, 2011-5355 2010-3938 2010-4147 2010-6965
Available from: 2014-04-04 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Tahir, A. M., Amberg, G. & Do-Quang, M. (2013). Initial rapid wetting in metallic systems. Acta Materialia, 61(14), 5375-5386
Open this publication in new window or tab >>Initial rapid wetting in metallic systems
2013 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 61, no 14, p. 5375-5386Article in journal (Refereed) Published
Abstract [en]

The initial rapid wetting of a solid surface by a liquid phase is an important step in many industrial processes. Liquid-phase sintering of powder metallurgical steels is one such industrial process, where metallic powders of micrometer size are used. Investigating the dynamic wetting of a high-temperature metallic drop of micrometer size experimentally is very challenging. Here, a phase-field-based numerical model is first implemented and verified by accurately capturing the initial dynamic wetting of millimeter-sized metal drops and then the model is extended to predict the dynamic wetting of a micrometer-sized metal drop. We found, in accordance with recent observations, that contact line friction is required for accurate simulation of dynamic wetting. Our results predict the wetting time for a micrometer-sized metal drop and also indicate that the dynamic wetting patterns at the micro- and millimeter length scales are qualitatively similar. We also found that the wetting process is much faster for a micrometer-sized metal drop compared to a millimeter-sized metal drop.

Keywords
Dynamic wetting, Phase field, Contact line friction, Millimeter- and micrometer-sized Cu drop, Powder metallurgical steels
National Category
Metallurgy and Metallic Materials Engineering and Technology
Identifiers
urn:nbn:se:sh:diva-30177 (URN)10.1016/j.actamat.2013.05.026 (DOI)000322750800022 ()2-s2.0-84882452190 (Scopus ID)
Available from: 2013-09-05 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Engblom, S., Do-Quang, M., Amberg, G. & Tornberg, A.-K. (2013). On diffuse interface modeling and simulation of surfactants in two-phase fluid flow. Communications in Computational Physics, 14(4), 879-915
Open this publication in new window or tab >>On diffuse interface modeling and simulation of surfactants in two-phase fluid flow
2013 (English)In: Communications in Computational Physics, ISSN 1815-2406, E-ISSN 1991-7120, Vol. 14, no 4, p. 879-915Article in journal (Refereed) Published
Abstract [en]

An existing phase-fieldmodel of two immiscible fluids with a single soluble surfactant present is discussed in detail. We analyze the well-posedness of the model and provide strong evidence that it is mathematically ill-posed for a large set of physically relevant parameters. As a consequence, critical modifications to the model are suggested that substantially increase the domain of validity. Carefully designed numerical simulations offer informative demonstrations as to the sharpness of our theoretical results and the qualities of the physical model. A fully coupled hydrodynamic test-case demonstrates the potential to capture also non-trivial effects on the overall flow.

Keywords
Cahn-Hilliard equation, Ginzburg-Landau free energy, Phase-field model, Surface active agent, Well-posedness
National Category
Computational Mathematics Engineering and Technology
Identifiers
urn:nbn:se:sh:diva-30131 (URN)10.4208/cicp.120712.281212a (DOI)000322071000002 ()2-s2.0-84877707309 (Scopus ID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2013-08-19 Created: 2016-06-01 Last updated: 2017-11-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2830-0454

Search in DiVA

Show all publications