Cross-basin multi-scale calculation method based on second-order nonlinear constitutive model

Abstract

The invention discloses a cross-basin multi-scale calculation method based on a second-order nonlinear constitutive model. This second-order nonlinear constitutive model, starting from the model of moment method and without simplification, directly adopts the Eu closure method to close the left end of the stress and heat flux transport equation, and then introduces Rayleigh method into the solution of the second-order constitutive model. Onsager dissipation function reduces the nonlinear algebraic equations to an equation about dissipation function R, and the steepest descent method is used tosolve the R equation of monoatomic and diatomic gases, and the corresponding stresses, heat flux and additional volume stresses of gases are obtained. It makes up for the shortcomings of NS equationin solving rarefied flow and cross-basin problems, and provides an effective solution for transitional flow, rarefied flow and multi-scale flow. In order to shorten the convergence time and improve the computational efficiency, a variety of iterative methods are used in the numerical solution of the method.

Description

technical field [0001] The invention relates to a cross-watershed multi-scale calculation method based on a second-order nonlinear constitutive model, which is suitable for gas dynamic numerical calculation methods under different Knudsen numbers, and is especially suitable for calculation states such as multi-scale cross-watershed. Background technique [0002] The height range from 20km to 100km is defined as the adjacent space, which has aroused people's extensive attention in recent years. In adjacent space, the physical properties of the gas, including density, pressure and temperature, vary with altitude. Since the adjacent space is between the continuous dense atmosphere and the thin near-space orbit, the particularity of the space environment determines that when the aircraft flies in this airspace at high speed, high maneuverability, and long endurance, it must consider the impact of the low-density atmosphere and high-temperature thermal environment on the air of t...

AI Technical Summary

Problems solved by technology

Although some breakthroughs have been made in the previous theoretical and computational studies of the generalized fluid dynamics equations, the hypersonic thermochemical non-equilibrium flow of high-temperature and rarefied gases in adjacent spaces is a very difficult multi-physics field coupling both in theoretical calculations and experimental simulations. multiscale flow

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