A two-fluid model for stratified flows with curved interfaces

This study is motivated by the need to develop a practical tool for predicting the interface shape in stratified flow of a general two-fluid system. A configuration of a curved interface is considered. A two-fluid model is used to solve the momentum equations for a variable interface curvature. Energy considerations provide a closure relation for the interface curvature. The analysis identifies all the input dimensionless parameters which determine the solution for the stratified flow pattern. When these are given, a complete solution of the problem is obtained, including the interface shape, in situ hold-up and pressure drop. The validity of the two-fluid model is evaluated by comparing its prediction with available experimental data and with the results of exact analytical solutions for laminar flows with curved interfaces. Thus, the conventional two-fluid model has been extended to tackle stratified flow with curved interfaces and various flow regimes, in which case analytical solutions are complicated and restricted to laminar flows.