Dissertation > Mathematical sciences and chemical > Mechanics > Fluid Mechanics

Three-dimensional NS equations numerically and SA turbulence model applied research

Author LiGuangNing
Tutor LiJie
School Northwestern Polytechnical University
Course Fluid Mechanics
Keywords Euler equations Navier-Stokes equations Jameson centered finite volume artificial viscosity formats Explicit four-step Runge-Kutta format Local time step Implicit residual smoothing Turbulence model Baldwin-Lomax model Spalart-Allmaras model
Type Master's thesis
Year 2006
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By solving the Euler equations simulate the real flow field characteristics, has become increasingly unable to meet the design requirements of modern aircraft and needs, in order to more accurately simulate the flow field information, providing detailed, efficient and practical aerodynamic data, Navier-Stokes ( NS) equations numerically discipline of computational fluid dynamics technology has become an important research direction. In addition, the nature and practice of science and engineering flow phenomena that exist in most of the turbulence phenomena, we discuss the numerical simulation of complex flow phenomena, naturally it is inseparable from the phenomenon of turbulence research and simulations. Based centered finite volume method, using an explicit four-step Runge-Kutta time marching format NS equations numerically, the choice of an equation Spalart-Allmaras turbulence model for viscous flow field numerical simulation, and with the algebraic Baldwin-Lomax turbulence model Numerical simulation of viscous flow capacity were compared. This paper mainly for the following aspects of work: 1. Viscous grid generation technique. Boundary along the object surface using outward extrapolation method for solving elliptic partial differential equations and the method are combined to generate viscous computational grid. Method pushed outward algebraic grid generated by the method can guarantee that the inner layer near the surface of the mesh material with good orthogonality, and control the first layer of mesh to the object surface distance; using the control method Hilgenstock outside source term rotary elliptical boundary layer orthogonal grid and distance on the dual control to ensure smooth distribution grid and has a reasonably high quality. 2.N-S equations numerical solution method. Convective term spatial discretization improved \Artificial viscosity in the pressure sensing factor is improved so that a class TVD properties and effectively suppress untrue numerical oscillation to accommodate the higher Mach number flow field, that the format is more robust. Time format to promote the adoption of improved explicit four-step Runge-Kutta format, and using local time step, implicit residual smoothing accelerate the convergence measure. 3 turbulence models and numerical solution techniques studied. In this paper, selecting and solved an equation Spalart-Allmaras (SA) model, and the original one equation SA turbulence model equation is derived for the conservation form. SA turbulence model has certain separated flow simulation capabilities, on the wall

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