Direct Numerical Simulation and Modeling of Multiphase Flows
The approaches of viscous potential flow (VPF) and the dissipation method (DM) have been applied to the study of different problems in two-phase fluid dynamics. VPF approach assumes irrotational fluid motion considering viscous stresses in the normal stress balance across fluid-fluid interfaces. DM stems from the integration of the mechanical energy equation assuming irrotational motion except that continuity of tangential stress and, in some cases, of the tangential velocity is assumed at gas-liquid and liquid-liquid interfaces. The strategy of VPF has been applied in the analysis of stress-induced cavitation for axisymmetric flow past a sphere. Furthermore, VPF and DM analyses are performed to model the decay rate of oscillations and standing waves in spherical drops and bubbles as well as in the case of capillary-gravity waves on a plane interface. These purely irrotational theories have also been used in the analysis of the Kelvin-Helmholtz instability for two-phase flow in a channel and in an unbounded domain. The early stages of drop break-up by the high-speed gas stream behind a passing shock wave has been studied by linear stability analysis using the theory of the potential flow of two viscous fluids and other theories from the literature. In all the cases, solution of the resulting equations demands numerical methods. MSI software resources are used to this end. VPF has also been applied to model the nonlinear behavior of drop and bubbles using boundary-integral methods. In the past, this research group has also investigated the fundamental dynamics of three-dimensional motions of solid particles in Newtonian and viscoelastic fluids. The codes written to solve the governing equations for this problem have been compiled and run using MSI resources.