An embedded approach for immiscible multi‐fluid problems

Abstract

An embedded formulation for the simulation of immiscible multi-fluid problems is proposed. The method is particularly designed for handling gas-liquid systems. Gas and liquid are modeled using the Eulerian and the Lagrangian formulation, respectively. The Lagrangian domain (liquid) moves on top of the fixed Eulerian mesh. The location of the material interface is exactly defined by the position of the boundary mesh of the Lagrangian domain. The individual fluid problems are solved in a partitioned fashion and are coupled using a Dirichlet-Neumann algorithm. Representation of the pressure discontinuity across the interface does not require any additional techniques being an intrinsic feature of the method. The proposed formulation is validated and its potential applications are shown.

Virtual Liquid Water Intrusion in Fuel Cell Gas Diffusion Media

“…The average in-plane (x and y) formation factor is 0.411 for the dry GDL reconstruction which agrees with experimental in-plane formation factor values in the range of 0.31-0. 54 17 for the Toray TGP-H-120 sample with 10% PTFE loading and porosity in the range of 0.61-0.73. The through-plane (z) formation factor for the dry GDL reconstruction is 0.224 which is also in agreement with previously reported experimental values in the range of 0.14-0.33 for Toray 120 samples.…”

“…The Lattice-Boltzmann method is the most commonly used multi-physics based technique to study water transport in fuel cell porous media. 4,33,[41][42][43][44][45] Eulerian-Lagrangian formulations [54][55][56] and volume of fluid (VOF) methodologies 57-59 could however also be applied. LBM is able to capture the intricate dynamics of liquid water and water droplets with the porous media as opposed to the other methods which assume a quasi-static water front.…”

On the application of the PFEM to droplet dynamics modeling in fuel cells

“…Conceptually, the embedded framework for multi-phase analysis was proposed in [30,Chap. 5] and [27], and extended to account for surface tension in [31] and [21].…”

“…Discretized governing equations are solved using a monolithic scheme, where both velocity and pressure are solved simultaneously at every time step. This method is more computationally intensive, but the presence of surface tension precludes using computationally cheaper schemes such as fractional step method [31]. In the present work, surface tension is modeled implicitly.…”

“…Pressure and convection stabilization terms are omitted here for the sake of brevity. They can be found in [31]. For reducing the computational cost associated to the solution of the governing system, the fractional splitting is applied [9,11,18,33].…”