Numerical study of droplet dynamics in a polymer electrolyte fuel cell gas channel using an embedded Eulerian-Lagrangian approach

Abstract

h i g h l i g h t sWe model the droplet dynamics on a PEFC cathode gas channel with a novel technique. A simple method to obtain interface curvature in two dimensions is given. Dynamic contact angle condition for droplets on rough surfaces is presented. Results can predict several variables of interest and agree with experimental data. a b s t r a c tAn embedded Eulerian-Lagrangian formulation for the simulation of droplet dynamics within a polymer electrolyte fuel cell (PEFC) channel is presented. Air is modeled using an Eulerian formulation, whereas water is described with a Lagrangian framework. Using this framework, the gas-liquid interface can be accurately identified. The surface tension force is computed using the curvature defined by the boundary of the Lagrangian mesh. The method naturally accounts for material property changes across the interface and accurately represents the pressure discontinuity. A sessile drop in a horizontal surface, a sessile drop in an inclined plane and droplets in a PEFC channel are solved for as numerical examples and compared to experimental data. Numerical results are in excellent agreement with experimental data. Numerical results are also compared to results obtained with the semi-analytical model previously developed by the authors in order to discuss the limitations of the semi-analytical approach.

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].…”

“…In the present work, surface tension is modeled implicitly. The details on the surface tension model can be found in [21].…”

“…When a droplet is placed on a solid substrate, three surface free energies are in equilibrium [20,21] γ SL (solid-liquid), γ LG (liquid-gas), and γ SG (solid-gas). At Γ S (Fig.…”

“…2), since curvature is zero, surface tension is also zero. At the contact line, the surface tension term is added using the normal vector corresponding to the static equilibrium configuration n eq instead of the actual normal vector n. More details on this condition can be found in reference [21]. The contact angle condition is validated in this example.…”

“…(21) and update the corresponding mesh position. Output: new position of the Lagrangian mesh,v n+1pn+1 in Ω n+1 Identify the position of Lagrangian domain within the Eulerian one.…”