Abstract: According to the physical characteristics of strong discontinuity at early stage of air explosion and its contact discontinuities at late stage, a new method coupling the ghost fluid method(GFM) with real GFM (RGFM) is proposed to treat the interface. At the initial stage, the situation where high density ratio and pressure ratio co-exist is treated by RGFM, while at the late stage, because explosion pressure, density and velocity, et al. Come close to each other, GFM is used to treat the interface. The moving interface is tracked by Local Level Set method. The governing equations are discredited by high resolution 5th-order weighted essentially non-oscillatory (WENO) scheme and 3rd-order TVD Runge-Kutta scheme. The air explosion is programmed. Using this program, air explosion at different heights and different distances are simulated. The simulation results accord well with the results obtained from empirical formula and experiments, which satisfactorily reflects the shock wave generation, propagation, reflection from the ground, and diffraction of shock wave, and the expansion of explosion products. The result shows that this method can be employed to simulate air explosion, and the explosion wave has good symmetry during propagating. The approach is effective for simulating the interaction of multi-medium flows at high density ratio and pressure ratio.

Key words: explosion mechanics, weighted essentially non-oscillatory, real ghost fluid method, numerical simulation, air explosion, high resolution