A Fraction Step Method Based on Adaptive Reaction Time Step and Its Application for High-speed Stiff Reacting Flows

摘要

The fraction step method is a practical approach for multi-dimensionalrnreactive flows. However, the computational efficiency of this method dropsrnsharply if the stiffness is increasing gradually. The reason for thisrnphenomenon is that most of computing times are wasted in the reaction step.rnIn order to overcome this shortage, a new fraction step based on adaptivernreaction time step is proposed. The core idea of this proposed method is tornreplace the constant number of sub reaction step used in the general fractionrnstep method by a reasonable minimum number of sub reaction steps forrneach cell at each time step. In order to show the advantage of the proposedrnmethod in computational efficiency, several classical high-speed stiffrnreacting flows are applied from different perspectives (such as differentrnreaction models, different flow time steps and different computationalrndomain sizes). The numerical results show that the new fraction steprnmethod not only can obtain reasonable results, but also has much higherrncomputational efficiency for stiff reacting flows.