No abstract

No abstract

Summary The simple low‐dissipation advection upwind splitting method (SLAU) scheme is a parameter‐free, low‐dissipation upwind scheme that has been applied in a wide range of aerodynamic numerical simulations. In spite of its successful applications, the SLAU scheme could be showing shock instabilities on unstructured grids, as many other contact resolved upwind schemes. Therefore, a hybrid upwind flux scheme is devised for improving the shock stability of SLAU scheme, without compromising on accuracy and low Mach number performance. Numerical flux function of the hybrid scheme is written in a general form, in which only the scalar dissipation term is different from that of the SLAU scheme. The hybrid dissipation term is defined by using a differentiable multidimensional‐shock‐detection pressure weight function, and the dissipation term of SLAU scheme is combined with that of the Van Leer scheme. Furthermore, the hybrid dissipation term is only applied for the solution of momentum fluxes in numerical flux function. Based on the numerical test results, the hybrid scheme is deemed to be a successful improvement on the shock stability of SLAU scheme, without compromising on the efficiency and accuracy. Copyright © 2016 John Wiley & Sons, Ltd.

No abstract

No abstract

No abstract

No abstract

Rotated upwind schemes have been evaluated as carbuncle-free shock-capturing methods. In order to reveal the relation between the rotated upwind-differencing direction and the performance of rotated upwind schemes, theoretical and numerical investigations are made. Three commonly used upwind schemes, including Roe scheme, AUSM + scheme and Van Leer scheme are investigated. According to the theoretical analysis, the dissipative terms of each upwind scheme are changed by the rotation procedure. Especially, the dissipative density term in the numerical flux function of rotated upwind schemes introduces extra dissipation. The numerical cases include simulations of laminar boundary layer, steady twin vortices and strong shock. The numerical results show that the carbuncle phenomenon can be eliminated by rotated upwind schemes, and the contact resolving capability of rotated upwind schemes is deteriorated by the rotation procedure. Monotonicity of the dissipation with rotation angle is also shown in the numerical results. Therefore, a novel rotation strategy that defines the rotation angle by a pressure weight function is introduced for tuning the dissipative effects adaptively. This strategy shows not only carbuncle-free result in hypersonic inviscid flow simulations, but also accurate results in viscous flow simulations.