Direct Numerical Simulation of Bubbly Flow and Modeling of Averaged Equation and Constitutive Equations

Abstract

We survey some numerical simulation methods for dispersed flows and point out that the vorticity generation mechanism due to the horizontal gradient of the void fraction is regarded in the conventional bubbly flow simulation based on the averaged equation, while one due to the boundary condition on the bubble-liquid interface is disregarded. In order to make clear the local structure of the pseudo turbulence in the bubbly flow, the direct numerical simulation of the Multi-bubble system is carried out. The simulation based on the averaged equation is also carried out. Constitutive equations, where not only SGS stresses but also boundary conditions of the pressure and the vorticity on the interface are taken into account, are derived for the averaged equations.