A priori analysis of an Isothermal, Turbulent Two-Phase Flow

Abstract

A novel approach to the simulation of isothermal, turbulent two-phase (liquid/vapour) flow of one substance is presented. The two-phase flow is modeled with a “one-fluid" formulation by means of a diffuse-interface concept and of the frame-invariant Korteweg tensor of capillary stresses at the interface. A single system of compressible Navier-Stokes equations can be written for the whole flow domain, the fluid properties being described by continuous functions of the mass density. The Van der Waals equation of state accounts for the variation of pressure with density at a given value of temperature slightly below the critical isotherm. After description of the numerical method, results of the Direct Numerical Simulation of a classic benchmark problem are shown. Next, two-phase subgrid terms related to the nonlinear pressure and capillary terms are studied by means of an a priori analysis based on DNS results, and a subgrid model for these terms is proposed.