Academy of Mathematics and Systems Science, CAS                         Colloquia & Seminars                                                   |                                                                                                                           | Speaker: |                                                 杜洁 助理教授 ,清华大学丘成桐数学科学中心                          |                                                                  | Inviter: |                          |                                                                                          Title:                          |                         High order bound              preserving methods for compressible multi-species flow with chemical              reactions |                                                                                          Time & Venue:                          |                         2021.11.25 10:00-11:00              腾讯会议ID:376 775 451 |                                                                                          Abstract:                          |                                                 In this talk, we develop third-order conservative sign-preserving                and steady-state preserving time integrations and seek their applications                in multispecies and multireaction chemical reactive flows. In this                problem, the density and pressure are nonnegative, and the mass                fraction should be between 0 and 1. There are four main difficulties                in constructing high-order bound-preserving techniques for multispecies                and multireaction detonations. First of all, most of the bound-preserving                techniques available are based on Euler forward time integration.                Therefore, for problems with stiff source, the time step will be                significantly limited. Secondly, the mass fraction does not satisfy                a maximum principle and hence it is not easy to preserve the upper                bound 1. Thirdly, in most of the previous works for gaseous denotation,                the algorithm relies on second-order Strang splitting methods where                the flux and stiff source terms can be solved separately, and the                extension to high-order time discretization seems to be complicated.                Finally, most of the previous ODE solvers for stiff problems cannot                preserve the total mass and the positivity of the numerical approximations                at the same time. In this work, we will construct third order conservative                sign-preserving Rugne-Kutta and multistep methods to overcome all                these difficulties. The time integrations do not depend on the Strang                splitting, i.e. we do not split the flux and the stiff source terms.                Moreover, the time discretization can handle the stiff source with                large time step and preserves the steady-state. Numerical experiments                will be given to demonstrate the good performance of the bound-preserving                technique and the stability of the scheme for problems with stiff                source terms.                         会议链接:https://meeting.tencent.com/dm/iKV4Jv5wKeXP                          |                                                                   |                                                                           |                                                                |