A Two-Phase Flow Computation Code Based on Two-Fluid Seven-Equation Model

Abstract

Abstract The present work is developing a computation code based on two-fluid seven-equation model. This model is fully non-equilibrium. It not only assumes two phases are mechanical and thermal non-equilibrium, but also it assumes the pressure is non-equilibrium. The governing equations include seven partial differential equations, which are two continuity equations, two momentum equations, two energy equations, and one volume fraction evolution equation. The computation framework is based on split scheme, including Godunov split and Strang split, and the problem is split into two independent subproblems. One is a homogenous partial differential equation (PDE) problem, and the other one is an ordinary differential equation (ODE) problem. The homogenous PDE problem is reduced to linear equation by a Roe-type Riemann solver, and the linear equation is solved by upwind and MUSCL-Hancock (MHM) scheme. The ODE problem is solved by an implicit ODE solver, including Euler backward method, trapezium rule method and TR-BDF2. This code is verified by three types of problems. MHM converges faster than upwind for smooth solution problem, however MHM’s convergency rate is not always large than that of upwind for shock problem. The source term problem shows that the calculation result is sensitivity to the numerical schemes.