NUMERICAL SIMULATION OF FREE EXPLOSION IN AIR USING DISCONTINUOUS GALERKIN METHOD

摘要

It is difficult to specify the design load in codes in case of an explosion event due to its complexity. Every defined event has to be uniquely examined, which necessitates numerical simulation of blast wave propagation in explosion scenarios.In order to conduct the above work, investigation into the spherical blast waves is a good start. Experiments have shown that the resulting flow for spherical free explosion is quite complex and a second shock wave can arise between the contact discontinuity and the rarefaction wave. The discontinuous Galerkin (DG) method has become a very popular numerical technique applied to computational fluid dynamics(CFD). Its popularity is mainly due to the fact it is highly accurate, compact, robust,trivially parallelizable, and that it can easily handle complex geometries. In this paper, we seek to make use of DG method to numerically simulate spherical free explosion in air and successfully capture the second shock wave (which does not exist in the one-dimensional shock tube problem). It is noted that implementation of DG method will produce extra volume integral term, which will introduce additional computational overhead because of the use of accurate numerical quadrature rule.To overcome this problem and optimize the DG solver, we develop a new version of quadrature-free DG method based upon Lagrange interpolate polynomial. Using this new scheme, the required computational time and storage memory can be significantly reduced and implementation can be simpler. Finally, the numerical results are also compared with those obtained experimentally.