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Modeling the Dynamics of Partial Wetting Depending on the Solid Microstructure and Applied Electric Potentials Using the SPH Method
von Philip KunzThe description of wetting phenomena on the continuum scale is a challenging problem in many engineering applications. Recently, these effects were included in the smoothed particle hydrodynamics method (SPH) by introducing a contact line force (CLF) on the continuum scale. In this thesis, the CLF model is employed to simulate two-phase flow in solid microstructures.
In cooperation with the Environmental Hydrology Group of the Utrecht University, drainage experiments in a micro-model were performed which allowed the visualization of interface propagation in detail. Especially, the flow path and the evolution of the capillary pressure observed in the experiments could be reproduced by the SPH simulations.
Apart from those good correlations, it was found taht the SPH simulations predict more then ten time higher dynamics than observed by the experiments.
On that basis it was assumed that surface roughness and sticking effects play a major role. It is indeed expected that most of the driving force is dissipated to overcome strong liquid–solid interactions, which were not accounted for in the existing CLF model.
Therefore, two different extended models are presented to account for stick-slip behavior of the contact line, caused by solid–liquid interactions. The respective models are the stick-slip viscosity model (SSV) and the stick-slip resistive force model (SSF).
In addition to the presented models which address the simulation of contact-line dynamics, two new algorithms for open boundary treatment in ISPH were introduced, where the inflow/outflow is driven by true Dirichlet boundary conditions of the projected pressure field.
Besides the influence of solid surface heterogeneities on wetting dynamics, the influence of an applied electric potential on the wetting behavior of electroconductive liquids was studied. In chemical engineering, such conditions are likely to happen in a gas diffusion electrode.
In cooperation with the Environmental Hydrology Group of the Utrecht University, drainage experiments in a micro-model were performed which allowed the visualization of interface propagation in detail. Especially, the flow path and the evolution of the capillary pressure observed in the experiments could be reproduced by the SPH simulations.
Apart from those good correlations, it was found taht the SPH simulations predict more then ten time higher dynamics than observed by the experiments.
On that basis it was assumed that surface roughness and sticking effects play a major role. It is indeed expected that most of the driving force is dissipated to overcome strong liquid–solid interactions, which were not accounted for in the existing CLF model.
Therefore, two different extended models are presented to account for stick-slip behavior of the contact line, caused by solid–liquid interactions. The respective models are the stick-slip viscosity model (SSV) and the stick-slip resistive force model (SSF).
In addition to the presented models which address the simulation of contact-line dynamics, two new algorithms for open boundary treatment in ISPH were introduced, where the inflow/outflow is driven by true Dirichlet boundary conditions of the projected pressure field.
Besides the influence of solid surface heterogeneities on wetting dynamics, the influence of an applied electric potential on the wetting behavior of electroconductive liquids was studied. In chemical engineering, such conditions are likely to happen in a gas diffusion electrode.