The laminar and turbulent flows past an axi-symmetric body with a ring wingwere investigated numerically at various attack angles (0°-20°) for the Reynolds numbers rangingfrom 10~3 to 10~7. The DDM (Domain D...The laminar and turbulent flows past an axi-symmetric body with a ring wingwere investigated numerically at various attack angles (0°-20°) for the Reynolds numbers rangingfrom 10~3 to 10~7. The DDM (Domain Decomposition Method) with the Schwarz iterative method based onfinite difference approximation was applied to simulate this problem. The primitive variableformulation was used for the solution of the incompressible Navier-Stoke equations. The velocityfield was calculated from the unsteady momentum equation by marching in time. The continuityequation was replaced by a Poisson-type equation for the pressure with the Neumann boundaryconditions. The Baldwin-Lomax model was adopted to simulate turbulence effect. The leap frogimplicit iterative method was used for the time difference approximations. The computed pressure atthe front stagnation point is found to have a small deviation, less than 10%, from the theoreticalvalue. The outlet flux has a loss about 5%. The lift coefficients increase linearly with the attackangle, but for attack angles greater than 15° the lift coefficients show mild decrease. Thefriction drag coefficients are insensitive to the attack angles, but the pressure drag coefficientsincrease markedly with the attack angles. In addition, complex flow patterns are revealed within thevicinity of the ring wing.展开更多
This paper presents a higher order difference scheme for the computation of the incompressible viscous flows. The discretization of the two-dimensional incompressible viscous Navier-Stokes equations, in generalized cu...This paper presents a higher order difference scheme for the computation of the incompressible viscous flows. The discretization of the two-dimensional incompressible viscous Navier-Stokes equations, in generalized curvilinear coordinates and tensor formulation, is based on a non-staggered grid. The momentum equations are integrated in time using the four-stage explicit Runge-Kutta algorithm [1] and discretized in space using the fourth-order accurate compact scheme [2]. The pressure-Poisson equation is discretized using the nine-point compact scheme. In order to satisfy the continuity constraint and ensure the smoothness of pressure field, an optimum procedure to derive a discrete pressure equation is proposed [9][3] . The method is applied to calculate the driven cavity flow on a stretched grid with the Reynolds numbers from 100 to 10000. The numerical results are in very good agreement with the results obtained by Ghia et al [7] and include the periodic solutions for high Reynolds numbers.展开更多
文摘The laminar and turbulent flows past an axi-symmetric body with a ring wingwere investigated numerically at various attack angles (0°-20°) for the Reynolds numbers rangingfrom 10~3 to 10~7. The DDM (Domain Decomposition Method) with the Schwarz iterative method based onfinite difference approximation was applied to simulate this problem. The primitive variableformulation was used for the solution of the incompressible Navier-Stoke equations. The velocityfield was calculated from the unsteady momentum equation by marching in time. The continuityequation was replaced by a Poisson-type equation for the pressure with the Neumann boundaryconditions. The Baldwin-Lomax model was adopted to simulate turbulence effect. The leap frogimplicit iterative method was used for the time difference approximations. The computed pressure atthe front stagnation point is found to have a small deviation, less than 10%, from the theoreticalvalue. The outlet flux has a loss about 5%. The lift coefficients increase linearly with the attackangle, but for attack angles greater than 15° the lift coefficients show mild decrease. Thefriction drag coefficients are insensitive to the attack angles, but the pressure drag coefficientsincrease markedly with the attack angles. In addition, complex flow patterns are revealed within thevicinity of the ring wing.
基金The project was supported by the Natural Science Foundation of Zhejiang Province(196045)the National Natutal Science Foundation of China(19472055).
文摘This paper presents a higher order difference scheme for the computation of the incompressible viscous flows. The discretization of the two-dimensional incompressible viscous Navier-Stokes equations, in generalized curvilinear coordinates and tensor formulation, is based on a non-staggered grid. The momentum equations are integrated in time using the four-stage explicit Runge-Kutta algorithm [1] and discretized in space using the fourth-order accurate compact scheme [2]. The pressure-Poisson equation is discretized using the nine-point compact scheme. In order to satisfy the continuity constraint and ensure the smoothness of pressure field, an optimum procedure to derive a discrete pressure equation is proposed [9][3] . The method is applied to calculate the driven cavity flow on a stretched grid with the Reynolds numbers from 100 to 10000. The numerical results are in very good agreement with the results obtained by Ghia et al [7] and include the periodic solutions for high Reynolds numbers.
