Permeation of oil‐in‐water emulsions through coalescing filter: Two‐dimensional simulation based on phase‐field model

The permeation of an oil‐in‐water emulsion through a coalescing filter is studied numerically. Our simulation model is based on the phase‐field model owing to its simple description of the wetting behavior of oil droplets on versatile surfaces. To realize two‐dimensional (2D) simulations of the coalescing processes, we construct a 2D filter model which describes the cross‐sectional structure of a fibrous filter in a simple manner. We investigate the effects of wettability, permeation flux, and fiber diameter on coalescing behavior. Oil droplets attach to the fibers and coalesce with each other, forming a bridging structure between fibers which promotes droplet coalescence unless the bridging structure blocks the entire flow path. This coalescence‐promoting effect of the bridging structure is observed under conditions where the fluid velocity inside a pore is relatively large. We demonstrate that our numerical model provides useful information to effectively design a coalescing filter and process.