Affordable robust moment closures for CFD based on the maximum-entropy hierarchy

摘要: The use of moment closures for the prediction continuum and moderately non-equilibrium flows offers modelling numerical advantages over other methods. maximum-entropy hierarchy holds promise robustly hyperbolic stable equations, however their are two issues that limit practical implementation. Firstly, have a treatment heat transfer, fluxes cannot be written in closed form very expensive iterative procedure is required at every flux evaluation. Secondly, these same closures, there physically possible states which entropy-maximization problem has no solution entire framework breaks down. This paper demonstrates affordable closed-form inspired by can proposed. It known closing approach singularity as region non-solvability approached. shows that, far from disadvantage, this allows smooth accurate shock-wave structure, even high Mach numbers. presence unphysical ''sub-shocks'' within shock-profile predictions traditional long been regarded an unfortunate limitation moment-closure technique. realization shock profiles are, fact, methods with moderate number moments greatly increases method's applicability to high-speed flows. In paper, 5-moment system simple one-dimensional gas 14-moment realistic gases developed examined. Numerical shock-waves variety incoming flow numbers demonstrate both robustness accuracy closures.