Adaptive Unstructured Grid In The Numerical Simulation Of Detonation Waves

In this thesis, the generation and grid adaptivity of two-dimensional unstructured grids are studied. Unstructured adaptive gird flow simulation is applied to the calculation of high-speed compressible flows with chemical reaction. The following results are obtained:1. The advancing-front method is used to generate two-dimensional unstructured grids. The derivative of flow parameter is implemented as a criterion to detect high gradient regions of the flow. Local grid refinement is proposed to cope with such a problem. The calculation efficiency is enhanced.2. The second-order Godunov method based on adaptive unstructured grids is applied to solve two-dimensional Euler equations. Methods for the calculation of numerical conservative fluxes passing through the triangle edge are given. A new monotonicity constraint condition is presented as a complement. The results show that it performs well near the shock and does not change the accuracy in the smooth flow.3. The governing equation with chemical reacting flow is established. Using time splitting algorithm, the convection term is solved with the second-order Godunov method and the chemical reaction is coped with two-step model. Standing oblique detonation waves induced by an accelerating projectile are simulated numerically. The results are compared well with the data of the experiments.