Applications Of High-Order Accurate Weighted Compact Nonlinear Scheme To Complicated Low Speed Flows

High-order schemes have the advantage of high-resolution, lower dispersion and dis-sipation errors. As reveal the clear flow structure accurately over low-order schemes, high-order schemes are widely applied in studies such as computational aeroacoustics, large-eddy simulation of turbulent flows and direct numerical simulation. As the increase of aircraft performance, the accuracy requirement of aerodynamic character is more and more striction for engineering. While the application of high-order schemes in engineer-ing problems, especially the low-speed flow with complex geometry, is limited to grid-flexibility, robust and computational efficiency.For engineering problems, the boundary layer transion has great impact on friction drag and flow seperation point, as a result the accurate simulation of the boundary layer transion location is an important subject in engineering. Especially for the flow of mod-erate Reynolds number, in which the area of laminar and turbulent is comparable, either fully laminar model or fully turbulence model would result as significant error.As the progress of geometry conservation law, characteristic-based interface condi-tions and convergence acceleration, the capability of WCSN on complex flow is improved, which is the base of this thethis. The WCNS high-order scheme is used, the transition model is implemented, and the phenomenon in low-speed flow with complex geometry is studied in this thethis.This thethis contains seven chapters as follows:Chapter one is the introduction, the significance and background of the present re-search work is briefly introduced. The development process of high-order schemes and transition model is reviewed. And then the current work is described.Chapter two presents the numerical methods used in this thethis. The main contents include governing equations, spatial and temporal discretization, boundary condition and turbulence models.Chapter three accomplish the local correlation-based γ-Reθ transition model. The simulation of freestream turbulence intensity is studied, the empirical correlation is sup-plemented and calibrated base on the experiment data of flatplate.In chapter four, the NLR7301 airfoil is simulated. The effects of turbulence model and the overlap width are studied. With transition model, the laminar seperation buble on the front tip, the wall friciton drag distribution and seperation location are distinct, the simulation accuracy of boundary layer is improved. The influence of overlap width on aerodynamics character is predicted with the current methods.In chapter five, the simulations of trapezoidal wing high lift configuration are per-formed, and the effects of difference initial flow, transition model and the deflection of flap is presented. Compared with other computational results obtained by typical CFD solvers, both the force coefficients and the surface pressure distributions given in this pa-per got better accordance with the test data, more reasonable prediction of flow structure near stalling was got, and the hysteresis of static stall is repeated.In chapter six, a realistic complex large aircraft is simulated with fully turbulence model and transition model.Chapter seven reviews all works in this thethis and gives concluding remarks, inno-vative points and future research directions. Finally, the reference and acknowledgements are presented.