Entropy correction method oriented to hybrid gird high-precision resistance prediction

Abstract

The invention discloses an entropy correction method oriented to hybrid gird high-precision resistance prediction. A second-order upwind Roe flux difference splitting format is adopted for a main control equation convective item to conduct discretion, and a central difference format is adopted by a viscosity item to conduct discretion; on the basis of traditional Harten-Yee entropy correction, theratio of the normal velocity on an interface to the velocity on the interface serves as a judgment basis, the effect of entropy correction is reserved for the possible area of stationary points or shock waves, and an interface parallel to an airfoil flow direction is not subjected to entropy correction or subjected to entropy correction as less as possible; an S-A (Spalart-Allmaras) is adopted for a turbulence model, and a first-order upwind format is adopted for turbulence control equation space dispersion. The entropy correction method oriented to the hybrid gird high-precision resistance prediction has the advantages that the interface parallel to the airfoil flow direction is not subjected to entropy correction or subjected to entropy correction as less as possible while entropy correction of other areas is unchanged, so that true dissipation of the area is not changed as much as possible, thus the influence of the entropy correction on the resistance prediction precision is lowered to the minimum degree, and meanwhile, the program robustness brought by the entropy correction is reserved.

Description

technical field [0001] The invention relates to the field of aerodynamics, in particular to an entropy correction method for high-precision resistance prediction of mixed grids. Background technique [0002] The Roe scheme flux difference splitting scheme is a Godunov solver based on approximate Riemann decomposition, which has the advantages of small dissipation, high resolution of contact discontinuity, strong shock capture performance, and better simulation of boundary layer flow. It is widely used in the simulation of supersonic flow field. However, for certain problems, the Roe format sometimes does not satisfy the entropy condition, and unreal expansion waves will be generated, resulting in non-physical understanding. In the vicinity of strong shock waves and sonic points, entropy correction needs to be performed on the original Roe format. [0003] In the usual Harten-Yee entropy correction method, since the velocity in the normal direction of the airfoil is small, a...

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Problems solved by technology

However, this increases the dissipation of physical quantities on the interface, especially in the boundary layer, which has a great influence on the solution accuracy of the normal velocity of the object surface, resulting in the inability to accurately reproduce the velocity profile of the boundary layer and the tangent near the wall. stress, which biases the prediction of frictional resistance

Existing articles on the Roe format entropy correction method either evaluate the performance of the existing entropy correction, or eliminate the non-physical expansion shock wave by improving the entropy correction near the sonic expansion wave. Methods to improve the prediction accuracy of the internal resistance of the boundary layer, especially the article on improving the prediction accuracy of the three-dimensional unstructured grid resistance has not yet been seen

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