
Zhen-Guo YanState Key Laboratory of Aerodynamics
Zhen-Guo Yan
Doctor of Philosophy
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38
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- assistant researcher
Publications
Publications (38)
In situations where a wide range of flow scales are involved, the non‐linear scheme should be capable of both shock capturing and low‐dissipation. Most of the existing Weighted Compact Non‐linear Schemes (WCNS) are too dissipative and incapable of achieving fourth‐order for the two smooth stencils located on the same side of a discontinuity due to...
The flow environment of spacecrafts involves complex flow phenomena such as shock waves and turbulence. The coexistence of shock wave discontinuities and multiscale turbulent structures in the flow field poses significant challenges to high-order accurate numerical simulations. A sixth-order central/fifth-order upwind linear hybrid interpolation wa...
Multiscale compressible turbulent flow is widely present in the aerospace field, and the co-existence of shock wave discontinuities and multi-scale turbulence in the flow field poses significant challenges for high-fidelity numerical simulation. To design high-order nonlinear scheme to improve the accuracy of complex turbulence simulation with stab...
Interaction between turbulence and an airfoil is a significant aerodynamic noise source for many engineering applications when turbulence in the wake of upstream blades interacts with the leading edge of downstream blades. Modeling the oncoming turbulence as harmonic gusts is a common approach to study the noise generated by turbulence–airfoil inte...
Weighted compact nonlinear schemes (WCNSs) are a popular family of high‐resolution shock‐capturing schemes for simulating compressible flows, of which the nonlinear interpolation procedure is dominant for the performance. In this work, a simplified weighting strategy is introduced for the nonlinear interpolation procedure. Firstly, an equivalent we...
Purpose
The purpose of the present study is to develop a new numerical framework that can predict the supersonic base flow more accurately, including the development of axisymmetrically separated shear layer and recompression shock. To this end, two aspects are improved and combined, i.e. a newly self-adaptive turbulence eddy simulation (SATES) tur...
Weighted compact nonlinear schemes (WCNSs) represent a popular family of high-order methods used for simulating compressible flows. Within these methods , the nonlinear interpolation process is crucial for the scheme's ability to capture shocks. In this study, we introduce a generalized weighting framework that utilizes candidates of varying orders...
It is challenging to apply numerical simulations to accurately predict the stall behavior of aircraft equipped with high-lift devices. Simulations with Reynolds-Averaged Naviersingle bondStokes (RANS) models suffer from lack of the reliability at high angles of attack with separated and reattached boundary layers, whereas wall-resolved Large Eddy S...
Compressible turbulent flow widely exists in the aerospace field. The coexistence of shock discontinuity and multi-scale turbulence in the flow field poses a challenge for high-precision numerical simulation. To improve the accuracy of complex turbulence simulation, in the framework of the Weighted Compact Nonlinear Scheme (WCNS) scheme, a WCNS-T s...
Different from conventional streamwise-aligned riblets, converging and diverging (C-D) riblets are arranged obliquely along the main-flow direction, intending to induce a large-scale secondary flow that modulates or controls the existing large-scale vortical structures in wall turbulence. In this study, we perform direct numerical simulations of tu...
The discontinuous Galerkin spectral element method (DGSEM) is a compact and high-order method applicable to complex meshes. However, the aliasing errors in simulating under-resolved vortex flows and non-physical oscillations in simulating shock waves may lead to instability of the DGSEM. In this paper, an entropy-stable DGSEM (ESDGSEM) based on sub...
This paper studies the energy stability property of the correction procedure via reconstruction (CPR) method with staggered flux points based on second-order subcell limiting. The CPR method with staggered flux points uses the Gauss point as the solution point, dividing flux points based on Gauss weights, with the flux points being one more point t...
The interaction of turbulence with airfoil is an important noise source in many engineering fields, including helicopters, turbofans, and contra-rotating open rotor engines, where turbulence generated in the wake of upstream blades interacts with the leading edge of downstream blades and produces aerodynamic noise. One approach to study turbulence–...
An implicit-in-time discontinuous Galerkin (DG) solver has been developed for compressible flows, which adopts an adaptive time stepping strategy balancing different discretization errors. To study the effects of preconditioning for further speed-up, preconditioners based on Jacobi iteration, Gauss-Seidel iteration, incomplete LU factorization, and...
This paper further investigates the subcell limiting approach based on compact nonuniform nonlinear weighted (CNNW) schemes for high-order correction procedure via reconstruction (CPR) method. A special subcell limiting approach is considered, which makes the hybrid CPR-CNNW scheme only containing fifth-order CPR and fifth-order CNNW. Firstly, a tr...
This paper develops a shock capturing approach for high-order correction procedure via reconstruction (CPR) method with Legendre-Gauss solution points. Shock regions are treated by novel compact nonuniform nonlinear weighted (CNNW) schemes, which have the same solution points as the CPR method. CNNW schemes are constructed by discretizing flux deri...
Weighted Compact Nonlinear Scheme (WCNS) is improved by replacing the nonlinear explicit interpolation with a nonlinear compact interpolation. The non-oscillatory behaviour of the weighted technique and the spectral resolution of the compact interpolation are maintained together. In order to investigate the performance of implicit large eddy simula...
A balanced adaptive time-stepping strategy is implemented in an implicit discontinuous Galerkin solver to guarantee the temporal accuracy of unsteady simulations. A proper relation between the spatial, temporal and iterative errors generated within one time step is constructed. With an estimate of temporal and spatial error using an embedded Runge-...
By introducing hybrid technique into high-order CPR (correction procedure via reconstruction) scheme, a novel hybrid WCNS-CPR scheme is developed for efficient supersonic simulations. Firstly, a shock detector based on nonlinear weights is used to identify grid cells with high gradients or discontinuities throughout the whole flow field. Then, WCNS...
At high Reynolds numbers the use of explicit in time compressible flow simulations with spectral/hp element discretization can become significantly limited by time step. To alleviate this limitation we extend the capability of the spectral/hp element open-source software framework, Nektar++, to include an implicit discontinuous Galerkin compressibl...
To further improve the resolution of weighted compact nonlinear schemes(WCNS), a new 7th-order compact nonlinear interpolation method is proposed on the same stencil as 5th-order CRWENO scheme. Proper nonlinear weights are developed based on the Y type nonlinear weights, the properties of which are further analyzed in this paper. It is found that t...
Osher flux with a multi-dimensional entropy fix is applied for high order weighted compact nonlinear scheme (WCNS). The entropy fix technique is used to mainly improve the dissipation on the interfaces perpendicular to the shock wave, and can thus improve shock wave stability and may not influence contact resolution. The properties of the Osher flu...
Mzz Mao L. Chen Z. Wan- [...]
Zhen-Guo Yan
Near-space hypersonic flow usually has concomitant circumstances with multiple complex physical, chemical and fluid mechanicsuch as real gas effects, rarefied effects, and viscous interactions. Regarding the topic of multi-physics phenomena in the hypersonic flow past complex lift-body configurations, the studies on the hypersonic aerodynamic chara...
This paper presents an efficient procedure for overcoming the deficiency of weighted essentially non-oscillatory schemes near discontinuities. Through a thorough incorporation of smoothness indicators into the weights definition, up to ninth-order accurate multistep methods are devised, providing weighted essentially non-oscillatory schemes with en...
This paper proposes a new kind of nonlinear weights to improve accuracy and resolution of high-order weighted compact nonlinear scheme. The new nonlinear weights are constructed based on not only the ratios between different smoothness indicators but also their values. The values of smoothness indicators are explicitly considered in the basic formu...
Finite difference methods are always advancing to obtain higher spectral resolution with robust discontinuities-capturing capabilities. Following HWCNS formation, a new high-order nonlinear compact interpolation is proposed, then the seventh-order compact HWCNS scheme is developed and its spectrum feature is presented. Several typical cases are car...
Protuberances are widely used for the trip laminar-turbulent transition of boundary layers. A row of 1 mm height diamond and slop protuberances are installed on the compression surface of a hypersonic inlet model. High-order schemes are applied to simulating the forced-transition flows. The Spalart-Allmaras (SA) and shear stress transport (SST) tur...
With very high requirements on computation grids, poor stability property and low computational efficiency, the application of high-order schemes to hypersonic flow simulations is greatly constrained. Focusing on these problems, a 3rd-order hybrid cell-node and cell-center weighted compact nonlinear schemes (HWCNS3) is developed. Some improvements...
The quasi-linear spectral analysis method based on an approximate dispersion relation (ADR) can give spectral properties of nonlinear space-discrete schemes more accurately. It has become to be a very important tool for the assessment of nonlinear schemes up to date. However, some factors, such as time-discrete schemes and number of computation gri...
Low computational efficiency is an important factor constraining the application of high-order numerical methods. To improve the computational efficiency of hybrid cell-edge and cell-node dissipative compact scheme (HDCS), a generalized minimum residual (GMRES) algorithm suitable for multi-block structured grids is developed to accelerate simulatio...