A dynamic pore-network model with discrete microbubble transport

2026-10-07

AI Summary

This study addresses the challenge of simulating the coupled transport of discrete microbubbles and two-phase flow in porous media by proposing a hybrid pore-network model. The method integrates dynamic two-phase flow, Lagrangian particle tracking, and pore-scale Stokes simulations through an innovative coupling mechanism to simulate the free motion of microbubbles within liquid-filled pores of proton exchange membrane (PEM) electrolyzers. The model’s mass conservation and flow-coupling accuracy are rigorously validated. Results reveal that gravity significantly influences gas transport regimes: under high-gravity conditions, the bubble detachment radius decreases while the proportion of discrete bubble transport increases substantially. These findings provide a critical theoretical foundation for optimizing gas–liquid transport in electrolyzers.

Abstract

We develop a hybrid pore-network model (PNM) for discrete microbubble transport coupled to connected two-phase flow in porous media. We apply the model to simulate flow in the porous transport layer of a rotating proton exchange membrane (PEM) electrolyser. At sufficiently large apparent gravitational forces, bubbles growing at the catalyst layer can detach at sizes smaller than the characteristic pore size and move through liquid-filled pores via buoyancy and advection. The model couples a dynamic two-phase PNM to a Lagrangian bubble tracker. Pore-scale Stokes simulations in square throats provide closures for the bubble buoyancy velocity, the hydraulic resistance of bubble-occupied throats, and the reciprocal coupling between liquid flow and bubble motion. Verification tests assess conservation, pressure-flow coupling, bubble growth, advection, merging, trapping, and transfer to the connected gas phase. The network simulations show that increasing apparent gravitational forces shifts a larger fraction of the produced gas toward discrete-bubble transport. The increase mostly comes from a reduced detachment radius, which decreases bubble size and lets them move more freely through the network.

Problem

• microbubble transport
• pore-network model
• porous media
• two-phase flow
• PEM electrolyser

Innovation

• pore-network model
• microbubble transport
• Lagrangian bubble tracker
• two-phase flow
• PEM electrolyser