Bearbeiter: M.Sc. Philip Kunz
Motivation
In a large number of process engineering applications, the simultaneous transport of gas and liquid in micro-porous structures plays an important role. Examples comprise reaction in porous catalysts, reactive distillation, adsorption, including capillary condensation for gas separation, simultaneous heat and moisture exchange in air ventilation systems as well as oxygen supply and water removal over the cathode side of membrane fuel cells. The functional materials used in these cases allow an intensification of the processes, but often the occurring transport steps are not sufficiently understood and REV transport models are often based on empirical correlations. During the course of the NUPUS program (C15) the simulation method SPH was introduced with the aim to simulate multi-phase flows in porous media [1]. The work on the direct numerical simulation will be continued with focus on the validation of the dynamic wetting effects and the simulation of complex geometries in order to improve parameter identification of REV-models.
Model Concepts
Model Concepts In order to simulate two-phase transport in the porous medium we will use the grid-less method Smoothed-Particle Hydrodynamics (SPH) method [2]. The method uses interacting particles to represent the porous structure and the flowing continua. Within the method, the interaction of particles can be derived in a canonical way from the transport equations and therefore allows the comparison with grid-based methods. Every particle carries a state vector for phase density, viscosity, pressure, velocity and temperature. As the particle can move in a Lagrangian way, the method is especially suited for complex structures with moving liquid/gas interfaces.
Current State of the Work
Current State of the Work During the NUPUS project C15 a SPH-code has been developed which is able to describe the dynamics of two-phase interfaces and the corresponding contact-lines on solid walls[1]. Within another DFG-funded project „Simulation of the morphogenesis of open-porous materials” a parallelized SPH-code for structure formation processes in visco-plastic and elastic materials is developed. An additional project taking part in the DFG priority program 1423 “process spray” also uses a particle method to describe and predict the chemical and physical processes of structure formation of single droplets during the polymerization.
Further Work planned
The final goal is the ability to perform real scale multi-phase calculations with complex flow geometries. In order to simulate models with higher particle numbers, the current SPH-code for the simulation of multi-phase phenomena has to be merged into the existing SPH-code developed in the structure formation project. The static and dynamic contact angles have been validated for the new model during the previous project on flat surfaces. In the next step simulations will be compared to experiments performed by the Department of Earth Science at Utrecht University within the framework of NUPUS (NL4) [3]. Also the new contact-line model needs to be applied on more complex surfaces in order to simulate real structures.
References
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M. Huber, W. Säckel, M. Hirschler, U. Nieken
Volume reformulation of spatially varying interactions using the example of moving contact lines for a complete surface tension description
Proceedings to 8th international SPHERIC workshop, 2013 -
R. A. Gingold, J. J. Monaghan
Smoothed particle hydrodynamics: theory and application to non-spherical stars
Mon. Not. R. Astron. Soc., 181, 375-389 (1977) -
M. Yoneda, M. Takimoto, S. Koshizuka
Effects of Microstructures of Gas Diffusion Layer on the Two-Phase Flow Transport Properties
ECS Transactions (2007) 629-635