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



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.


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.

Wetting on a structured surface
Interface instability, using the example of a chain of droplets on the tap (photo and simulation)

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.

Simulation of the structure formation process of a porous structure from a polymer solution
Visualization of a simulation of 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.

Simulation of rigid body motion in a flowing fluid
Name Function
Research assistant
Research assistant
2 additional persons visible within KIT only.


Capillary adsorption of droplets into a funnel-like structure
Wu, Y.; Wang, F.; Huang, W.; Selzer, M.; Nestler, B.
2022. Physical Review Fluids, 7, Art.-Nr.: 054004. doi:10.1103/PhysRevFluids.7.054004
A Two-Dimensional Phase-Field Investigation on Unidirectionally Solidified Tip-Splitting Microstructures
Laxmipathy, V. P.; Wang, F.; Selzer, M.; Nestler, B.
2022. Metals, 12 (3), Art.-Nr.: 376. doi:10.3390/met12030376
Equilibrium droplet shapes on chemically patterned surfaces: theoretical calculation, phase-field simulation, and experiments
Wu, Y.; Kuzina, M.; Wang, F.; Reischl, M.; Selzer, M.; Nestler, B.; Levkin, P. A.
2022. Journal of Colloid and Interface Science, 606, 1077–1086. doi:10.1016/j.jcis.2021.08.029
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), Art:nr. 247. doi:10.1038/s41467-020-20498-1
Phase-field formulation of a fictitious domain method for particulate flows interacting with complex and evolving geometries
Reder, M.; Schneider, D.; Wang, F.; Daubner, S.; Nestler, B.
2021. International Journal for Numerical Methods in Fluids, 93 (8), 2486–2507. doi:10.1002/fld.4984
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
Phase-field investigation on the peritectic transition in Fe-C system
Cai, Y.; Wang, F.; Zhang, Z.; Nestler, B.
2021. Acta Materialia, 219, Art.-Nr.: 117223. doi:10.1016/j.actamat.2021.117223
Phase-Field Modeling of Multiple Emulsions Via Spinodal Decomposition
Zhang, H.; Wu, Y.; Wang, F.; Guo, F.; Nestler, B.
2021. Langmuir, 37 (17), 5275–5281. doi:10.1021/acs.langmuir.1c00275
Liquid Wells as Self-Healing, Functional Analogues to Solid Vessels
Scheiger, J. M.; Kuzina, M. A.; Eigenbrod, M.; Wu, Y.; Wang, F.; Heißler, S.; Hardt, S.; Nestler, B.; Levkin, P. A.
2021. Advanced Materials, 33 (23), Art.-Nr.: 2100117. doi:10.1002/adma.202100117
Multiphase-field model for surface diffusion and attachment kinetics in the grand-potential framework
Hoffrogge, P. W.; Mukherjee, A.; Nani, E. S.; Amos, P. G. K.; Wang, F.; Schneider, D.; Nestler, B.
2021. Physical review / E, 103 (3), Article no: 033307. doi:10.1103/PhysRevE.103.033307
Wetting transition and phase separation on flat substrates and in porous structures
Wang, F.; Nestler, B.
2021. Journal of Chemical Physics, 154 (9), Art.-Nr.: 094704. doi:10.1063/5.0044914
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
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
Progress Report on Phase Separation in Polymer Solutions
Wang, F.; Altschuh, P.; Ratke, L.; Zhang, H.; Selzer, M.; Nestler, B.
2019. Advanced materials, 31 (26), Art.Nr. 1806733. doi:10.1002/adma.201806733
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
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
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
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
Detachment of nanowires driven by capillarity
Wang, F.; Nestler, B.
2016. Scripta materialia, 113, 167–170. doi:10.1016/j.scriptamat.2015.11.002
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
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