The interface between the liquid and gas phase can sometimes become blurry. This could be due to physical properties (such as a breaking wave or sloshing in a vessel). Where the dispersed phase becomes entrained in the continuous phase, the inhomogeneous model is a better choice.

A technique to increase the mesh density in the region of a liquid-gas interface is to create a subdomain that occupies the same region as the liquid (or gas) phase, and inflate the mesh in both directions from the edge of the subdomain, as shown in Figure 10.1: An exaggerated view of three inflation layers on each side of the uppermost subdomain boundary surface.. The inflation layers can increase the resolution in the region of the interface and enhance the results.

Figure 10.1: An exaggerated view of three inflation layers on each side of the uppermost subdomain boundary surface.