Microstructure – Fluid Dynamics

The research of the group focuses on interfacial instability, wetting, and phase transitions in alloys and polymer solutions, where both fluid dynamics and diffusion are present and coupled.

Contact person: Dr.-Ing. Fei Wang

Research

By employing the phase-field method, the research of the group concentrates on the microstructural evolution process, where both fluid dynamics and diffusion are present. Two different phase-field approaches, namely Cahn-Hilliard and Allen-Cahn models, coupled with the Navier-Stokes equations, are adopted to model particular physical problems. The following research areas are considered.

Wetting

Different kinds of wetting phenomena are considered, such as reactive wetting in the process of soldering, inertial wetting on patterned structures, and wetting transitions in dependence of the temperature/composition.

Interfacial instability

When we open a water tap, the water trickles down and breaks apart into a chain of droplets, which is a typical interfacial instability in fluid dynamics. Similar to this, a thin liquid film may also break up into droplets or liquid rings. The problem becomes more complex if the liquid phase is in contact with a solid phase, where the wetting mechanism has to be considered. For this topic, we scrutinize the interfacial evolutions and instabilities by developing theoretical models and performing numerical simulations based on the phase-field methods.

Formation of porous structures from polymer solutions

Porous structures can be formed from polymer solutions via spinodal decomposition. During the structural formation process, two stages are assumed: At the first stage, the solution is considered to be a liquid phase, where the surface tension and phase transition dominate the microstructural evolution. At the second stage, gelation takes place, where the droplets resulting from the phase separation are solid-like. Here, viscoelastic properties have to be taken into account. We aim to develop a thermodynamically consistent phase-field model for this structure formation process.

Solidification

We adopt the phase-field model to study phase transition, such as dendrite growth, monotectic reaction, peritectic reaction, and eutectic reaction, where diffusion and convection are involved.

Rigid body motion

In contrast to the soft matter particles with finite deformations in the formation process of porous structures, we here consider rigid body particles, where the deformation is zero. For this topic, a phase-field model is currently being developed.

Team
Name	Function
Zhang, Haodong	Research assistant
Wu, Yanchen	Research assistant
Reder, Martin	Mitarbeiter
Veluvali, Pavan Laxmipathy
Enugala, Sumanth
Cai, Yuhan
1 additional person visible within KIT only.

Publications

2021

3D printing of inherently nanoporous polymers via polymerization-induced phase separation.
Dong, Z.; Cui, H.; Zhang, H.; Wang, F.; Zhan, X.; Mayer, F.; Nestler, B.; Wegener, M.; Levkin, P. A.
2021. Nature Communications, 12 (1), Article no: 247. doi:10.1038/s41467-020-20498-1

Phase-field simulations of grain boundary grooving under diffusive-convective conditions.
Laxmipathy, V. P.; Wang, F.; Selzer, M.; Nestler, B.
2021. Acta materialia, 204, Art.-Nr.: 116497. doi:10.1016/j.actamat.2020.116497

2020

Microstructural transition in monotectic alloys: A phase-field study.
Laxmipathy, V. P.; Wang, F.; Selzer, M.; Nestler, B.
2020. International journal of heat and mass transfer, 159, Art.-Nr. 120096. doi:10.1016/j.ijheatmasstransfer.2020.120096

How do chemical patterns affect equilibrium droplet shapes?.
Wu, Y.; Wang, F.; Ma, S.; Selzer, M.; Nestler, B.
2020. Soft matter, 16 (26), 6115–6127. doi:10.1039/d0sm00196a

A phase-field study on polymerization-induced phase separation occasioned by diffusion and capillary flow—a mechanism for the formation of porous microstructures in membranes.
Wang, F.; Ratke, L.; Zhang, H.; Altschuh, P.; Nestler, B.
2020. Journal of sol gel science and technology, 94 (1). doi:10.1007/s10971-020-05238-7

2019

Influence of melt convection on the morphological evolution of seaweed structures: Insights from phase-field simulations.
Pavan Laxmipathy, V.; Wang, F.; Selzer, M.; Nestler, B.; Ankit, K.
2019. Computational materials science, 170, Art.-Nr. 109196. doi:10.1016/j.commatsci.2019.109196

Phase-field investigation on the growth orientation angle of aluminum carbide with a needle-like structure at the surface of graphite particles.
Cai, Y.; Wang, F.; Selzer, M.; Nestler, B.
2019. Modelling and simulation in materials science and engineering, 27 (6), Art.-Nr.: 065010. doi:10.1088/1361-651X/ab2351

Progress Report on Phase Separation in Polymer Solutions.
Wang, F.; Altschuh, P.; Ratke, L.; Zhang, H.; Selzer, M.; Nestler, B.
2019. Advanced materials, 1806733. doi:10.1002/adma.201806733

Investigation of Equilibrium Droplet Shapes on Chemically Striped Patterned Surfaces Using Phase-Field Method.
Wu, Y.; Wang, F.; Selzer, M.; Nestler, B.
2019. Langmuir, 35 (25), 8500–8516. doi:10.1021/acs.langmuir.9b01362

Phase-field study on the growth of magnesium silicide occasioned by reactive diffusion on the surface of Si-foams.
Wang, F.; Altschuh, P.; Matz, A. M.; Heimann, J.; Matz, B. S.; Nestler, B.; Jost, N.
2019. Acta materialia, 170, 138–154. doi:10.1016/j.actamat.2019.03.008

2018

Phase-field modeling of reactive wetting and growth of the intermetallic Al2 Au phase in the Al-Au system.
Wang, F.; Reiter, A.; Kellner, M.; Brillo, J.; Selzer, M.; Nestler, B.
2018. Acta materialia, 146, 106–118. doi:10.1016/j.actamat.2017.12.015

Phase-field study of surface irregularities of a cathode particle during intercalation.
Santoki, J.; Schneider, D.; Selzer, M.; Wang, F.; Kamlah, M.; Nestler, B.
2018. Modelling and simulation in materials science and engineering, 26 (6), 065013. doi:10.1088/1361-651X/aad20a

2017

Numerical and experimental investigations on the growth of the intermetallic Mg₂Si phase in Mg infiltrated Si-foams.
Wang, F.; Matz, A. M.; Tschukin, O.; Heimann, J.; Mocker, B. S.; Nestler, B.; Jost, N.
2017. Advanced engineering materials, 19 (10), Art.Nr. 1700063. doi:10.1002/adem.201700063

Effect of capillarity on the breakup of liquid jets, interfacial wave and motion of droplets in immiscible liquids. PhD dissertation.
Wang, F.
2017. Karlsruher Institut für Technologie (KIT). doi:10.5445/IR/1000071294

2016

Detachment of nanowires driven by capillarity.
Wang, F.; Nestler, B.
2016. Scripta materialia, 113, 167–170. doi:10.1016/j.scriptamat.2015.11.002

2015

Underdamped capillary wave caused by solutal Marangoni convection in immiscible liquids.
Wang, F.; Ben Said, M.; Selzer, M.; Nestler, B.
2015. Journal of materials science, 51 (4), 1820–1828. doi:10.1007/s10853-015-9600-1

Experimental and Numerical Investigation on the Phase Separation Affected by Cooling Rates and Marangoni Convection in Cu-Cr Alloys.
Wang, F.; Klinski-Wetzel, K. von; Mukherjee, R.; Nestler, B.; Heilmaier, M.
2015. Metallurgical and materials transactions / A, 46 (4), 1756–1766. doi:10.1007/s11661-015-2745-3

A phase-field study on the formation of the intermetallic Al2Au phase in the Al-Au system.
Wang, F.; Nestler, B.
2015. Acta materialia, 95 (2), 65–73. doi:10.1016/j.actamat.2015.05.002

On the motion of droplets driven by solutal Marangoni convection in alloy systems with a miscibility gap.
Wang, F.; Selzer, M.; Nestler, B.
2015. Physica D: Nonlinear Phenomena, 307, 82–96. doi:10.1016/j.physd.2015.06.001

2014

Numerical study on solutal Marangoni instability in finite systems with a miscibility gap.
Wang, F.; Mukherjee, R.; Selzer, M.; Nestler, B.
2014. Physics of fluids, 26 (12), Art.Nr. 1.4902355. doi:10.1063/1.4902355