Simulation of Taylor Flow in Capillaries Based on the Volume-of-Fluid Technique

Taylor flow, a flow regime characterized by Taylor bubbles separated by liquid slugs that do not contain entrained micro bubbles, is a predominant gas-liquid two-phase flow regime in capillaries and minichannels (channels with hydraulic diameters in the 0.1-1 mm range), and it occurs in monolithic catalytic converters and other multiphase reactors. Taylor flow regime is morphologically relatively simple and has been modeled in the past using computational fluid dynamics (CFD) methods. However, most of the past CFD models have either assumed a fixed gas-liquid interfacial geometry or have modeled the gas-liquid interphase movement based on the method of spines, which imposes some restrictions on the free movement of the interface. In this study, we examine the feasibility of CFD modeling of the Taylor flow regime in capillaries by using the volume-of-fluid (VOF) technique for the motion of the gas-liquid interphase. It is shown that such a model predicts well the experimental data and empirical correlations relevant to the hydrodynamics of capillaries. Improved correlations for slug length and pressure drop in capillaries are also suggested based on available experimental data.