IMPROVEMENT OF INTERFACE TRACKING IN LAGRANGIAN PARTICLE METHOD FOR GAS-LIQUID TWO-PHASE FLOW

Abstract

An entrainment of air bubbles into water during wave breaking is the one of the key issues of the surfzone hydrodynamics. Therefore, recently, the numerical models to track the gas-liquid interface are being improved actively. The Lagrangian particle method, such as the SPH (smoothed particle hydrodynamics) and the MPS (moving particle semi-implicit) method, is one of the methods which can analyze the free surface flow based on the Navier-Stokes equation. The particle method shows good performance to simulate the fragmentation and the coalescence of liquid. The difficulties in the analysis of the gas-liquid interface by the two-phase flow model is the numerical instability due to the gas-liquid density difference. To overcome this problem, Koshizuka et al. developed the two-step pressure calculation algorithm, in which the pressure fields of liquid (=heavy fluid) and gas (=light fluid) are calculated separately. In this study, the Koshizuka model, which was applied to a vapor explosion, is modified to fit the phenomena treated in hydraulic engineering. The basic characteristics of the modified model are examined in the dam-break simulation.