Numerical Simulation of Three-Fluid Stratified Flow Using the Level-Set Method

Laminar three-fluid stratified flow which involves two different moving interfaces is numerically investigated in a two-dimensional domain in this paper. These interfaces are captured using the level-set method via two level-set functions. The effects of various parameters including Froude number Fr and Weber number We as well as the initial locations of the two interfaces on the evolution of the two interfaces are investigated. It is found that the decrease of We number increases the entry length. For a given volumetric flow rate ratio, the interfacial location at fully developed flow is identical irrespective of the Froude and Weber numbers as well as the initial interfacial location at the inlet. The interfacial locations for fully developed flow show distinct behaviors under different flow rate ratios and viscosity ratios. Increase of volumetric flow rate and viscosity for any one of the fluids increases the pressure drop in the channel. The study of pressure gradient reduction factor (PGRF) shows that it is possible to achieve pressure gradient reduction by introducing less viscous fluids in the transportation of a more viscous fluid.