COMPARISON OF PERFORMANCE OF DIFFERENT MULTIPHASE MODELS IN PREDICTING STRATIFIED FLOW

Stratified flow is one of the important multiphase flow patterns found in the petroleum industries, nuclear industries, chemical industries, etc. The key feature of this flow pattern is the presence of interface(s) separating the phases. The interface evolves with space and time. It is also subjected to the force of surface tension along with other intermolecular forces. Thus, it is necessary to capture the interface(s) of stratified flow in order to predict the characteristics of such flows. The complex nature of stratified flow essentially demands for the use of multiphase computational fluid dynamics for predicting them. The multiphase model, which is employed for the analysis, must be able to properly capture the evolving interface. The level-set method (LSM), volume of fluid method (VOF), etc., are popular methods used for this purpose. The combination of these two methods is known as the coupled level set and volume of fluid (CLSVOF), which is also becoming popular for the prediction of a stratified flow pattern. Another multiphase model, called the multifluid VOF (MVOF) model, is available in the recent versions of ANSYS Fluent, which has been developed with the aim that this would overcome the limitations of VOF. Thus, the present study aims at comparing the performance of three multiphase models, namely, CLSVOF, VOF, and MVOF, available in ANSYS Fluent (Version 15) with the experimental data of Elseth (Elseth, G., An experimental study of oil/water flow in horizontal pipes, PhD thesis, Norwegian University of Science and Technology, 2000) for the analysis of stratified flow.