Numerical Calculation And Application Research Based On Navier-Stokes Equations

With the development of computer technology,computational fluid dynamics(CFD)has been widely used and plays a very important role in the engineering fields,but it has some challenge problems.The accuracy of CFD methods and turbulence models are still the difficult issues when using CFD to solve the problems of the design,calculation and the flowing of complex geometry in modern industry.This paper focuses on the research of the accuracy of the CFD simulations and turbulence models.The major works and achievements are described as the following:Firstly,based on domain decomposition technique,A high quality and multi-block structured patched grid on the wing of ONERA M6 is generated by solving partial differential equations and basic algebraic methods.The performance of two different limiters: min-mod limiter and the modified 3rd-Upwind bias limiter are investigated by simulating the transonic fields around M6 Wing.The governing equations are the Reynolds-Averaged Navier-Stokes equations coupled with the Spalart-Allmaras(SA)one equation model.the spatial discretization adopts the flux difference splitting upwind scheme of Roe.The fully implicit method is used for time marching.Multi-grid method is employed to speed up the iterative convergence.The results show that the shock quality predicted by min-mod limiter is better than the modified 3rd-Upwind bias limiter.The modified 3rd-Upwind bias limiter has a faster speed of convergence and higher accuracy compared with the min-mod limiter.Secondly,based on the wing of ONERA M6,The performance of turbulence models and the effects of turbulence models on aerodynamic characteristics are investigated by solving Reynolds-Averaged Navier-Stokes equations coupled with three kinds of turbulence models:the Spalart-Allmaras(SA)one equation model,Wilcox's k-?(Wilcox)model and Menter's k-?SST(SST)two equation model.A modified 3rd-Upwind limiter is employed to improve the accuracy and avoid numerical oscillations near discontinuities.By comparing and analyzing the differences between different turbulence models,the satisfactory results are obtained.The results of this paper have some reference values for the selection and improvement of turbulence models.A general approach generating high quality multi-block structured patched grids is developed using the hypercube concept.A multi-block structured patched grid around the slender revolutionary body is generated.The separation flow field of the slender revolutionary body is simulated at the supersonic high attack angle by solving Reynolds-Averaged Navier-Stokes equations coupled with three kinds of turbulence models: the Spalart-Allmaras(SA)one equation model,Wilcox's k-?(Wilcox)model and Menter's k-? SST(SST)two equation model.The differences of SA,Wilcox and SST turbulence models are analyzed.The predicted pressure distributions on the surface are agree with the experiment.The main vorticity,vortex core position and secondary separation vortex near the wall surface are well simulated by three turbulent models.In this paper,the differences of different limiters and turbulence models are compared and analyzed,and the ideal results are obtained,which verifies the feasibility of the algorithm and the solution technique.The results of this paper have some reference values for improving the accuracy of CFD simulations,the improvement of turbulence models and the construction of limiters.