Deng Xiaogang

Investigation on Weighted Compact Fifth-order Nonlinear Scheme and Applications to Complex Flow

The Fourier analysis and applications of Weighted Compact Fifth-order Nonlinear Scheme, which is called as WCNS-E-5, are presented in this paper. Using weighted technique, the nonlinear adaptive solver automatically chooses the locally smoothest stencil, hence avoiding crossing discontinuities in the interpolations at cell-edges as much as possible. As one of the high-order WCNS developed before, WCNS-E-5 is of fifth-order accuracy in smooth region and third-order accuracy in the vicinity of discontinuities. By Fourier analysis the features of WCNS-E-5 are discussed in terms of dissipative and dispersive errors, the resolving efficiency and the multi-dimensional phase speed anisotropy in smooth regions. The analytical results show that WCNS-E-5 has better characteristics than EUW-5 in terms of dispersive and dissipative errors, and it also has the higher resolving efficiency than EUW-5 and e

A novel slightly compressible model for low Mach number perfect gas flow calculation

By analyzing the characteristics of low Mach number perfect gas flows, a novel Slightly Compressible Model (SCM) for low Mach number perect gas flows is derived. In view of numerical calculations, this model is proved very efficient, for it is kept within thep-v frame but does not have to satisfy the time consuming divergence-free condition in order to get the incompressible Navier-Stokes equation solution. Writing the equations in the form of conservation laws, we have derived the characteristic systems which are necessary for numerical calculations. A cell-centered finite-volume method with flux difference upwind-biased schemes is used for the equation solutions and a new Exact Newton Relaxation (ENR) implicit method is developed. Various computed results are presented to validate the present model. Laminar flow solutions over a circular cylinder with wake developing and vortex shedding are presented. Results for inviscid flow over a sphere are compared in excellent agreement with the exact analytic incompressible solution. Three-dimensional viscous flow solutions over sphere and prolate spheroid are also calculated and compared well with experiments and other incompressible solutions. Finally, good convergent performances are shown for sphere viscous flows.

Numerical Study for the Influence of High - pressure Glow Discharged -induced Plasma on the Flow in Boundary Region

The influence of electric field models on flow over a flat plate with a small electrode stripe is investigated in this paper. Two models are considered, one is the linear model of glow discharge-induced fluid dynamics given by Shyy et. al., the other is the traditional potential equation of electric field (called as Laplace model). The influence of the work done by electric forces is also investigated. Numerical results show that the influence of the electric field models on the flow is noticeable, and the two models perform very different effect on flow pattern and pressure distribution, however the work done by the electric forces has little influence on the flow since the power rate is very small due to the low velocity in the boundary layer. The pressure within the downstream of the electrode grows up because of the effect of electric field, and the shear stress increases due to the fluid acceleration by electric forces in boundary layer. These conclusions are reasonable and agree with those presented in the Ref. [1-4]. In addition, comparison of numerical results by the two models demonstrates that the increments of velocity and viscous stress by the Laplace model are higher than those by Shyy’s linear model in the vicinity of electrode, and smaller far away from the electrode.