Improvement of Two-Component Model of the Finite Difference Lattice Boltzmann Method for a Gas-Liquid Flow Simulation

An Improved model of the finite difference lattice Boltzmann method which allows us to consider gas-liquid two component flows with a large density ratio like air-water flows was proposed. Simulations of the two component fluids which have a free interface and a large density ratio were demonstrated. The model which has compressibility of fluid and allows us to consider the pressure waves propagating in water like water hammers was presented. The basic idea is to decrease a density fluctuation by giving a large pressure gradient. The compressibility of liquid was controlled by choosing the bulk modulus. In order to simulate immiscible two fluids, the modulated diffusion scheme proposed by Latva-Kokko et al. was employed. The scheme is able to produce a smooth interface by allowing a certain amount of interface diffusion. The continuum surface force proposed by Brackbill et al. was employed as surface tension. A collapse of liquid column was calculated in order to confirm the relation between the inertia of liquid with a large density and the gravity, and the appropriate result was obtained.