A hybrid central-upwind scheme is proposed. Two sub-schemes, the central difference scheme and the Roets flux difference splitting scheme, are hybridized by means of a binary sensor function. In order to examine the c...A hybrid central-upwind scheme is proposed. Two sub-schemes, the central difference scheme and the Roets flux difference splitting scheme, are hybridized by means of a binary sensor function. In order to examine the capability of the proposed hybrid scheme in computing compressible turbulent flow around a curved surface body, especially the flow involving shock wave, three typical eases are investigated by using detached-eddy simulation technique. Numerical results show good agreements with the experimental measurements. The present hybrid scheme can be applied to simulating the compressible flow around a curved surface body involving shock wave and turbulence.展开更多
The second-order moment combustion model, proposed by the authors is validated using the direct numerical simulation （DNS） of incompressible turbulent reacting channel flows. The instantaneous DNS results show the n...The second-order moment combustion model, proposed by the authors is validated using the direct numerical simulation （DNS） of incompressible turbulent reacting channel flows. The instantaneous DNS results show the near-wall strip structures of concentration and temperature fluctuations. The DNS statistical results give the budget of the terms in the correlation equations, showing that the production and dissipation terms are most important. The DNS statistical data are used to validate the closure model in RANS second-order moment （SOM） combustion model. It is found that the simulated diffusion and production terms are in agreement with the DNS data in most flow regions, except in the near-wall region, where the near-wall modification should be made, and the closure model for the dissipation term needs further improvement. The algebraic second-order moment （ASOM） combustion model is well validated by DNS.展开更多
This paper describes the design of a new kind of miniature abrading sphere, which is magnetically mounted inside a spherical gap and set in rotation pneumatically with air. Large eddy simulation is performed in conjun...This paper describes the design of a new kind of miniature abrading sphere, which is magnetically mounted inside a spherical gap and set in rotation pneumatically with air. Large eddy simulation is performed in conjunction with the compressible Smagorinsky model. Minimal temperature variation allows for the assumption of adiabatic walls. Fluid-solid interaction is modeled using the law of the wall for compressible turbulent flow. A parametric study is done to determine optimal geometric layout while taking physical restrictions into account. The resulting optimal configuration is then examined in detail in order to determine demands to be met by the computerized control of the magnetic bearing as well as to quantify the force available to the abrasion process. Finally, a mathematical relation is given that determines available abrasion force depending on standard volumetric flow rate and rotation frequency. The findings presented here provide a basis for further development of smaller versions of the tool.展开更多
In this paper,the discontinuous Galerkin(DG)method combined with localized artificial diffusivity is investigated in the context of numerical simulation of broadband compressible turbulent flows with shocks for under-...In this paper,the discontinuous Galerkin(DG)method combined with localized artificial diffusivity is investigated in the context of numerical simulation of broadband compressible turbulent flows with shocks for under-resolved cases.Firstly,the spectral property of the DG method is analyzed using the approximate dispersion relation(ADR)method and compared with typical finite difference methods,which reveals quantitatively that significantly less grid points can be used with DG for comparable numerical error.Then several typical test cases relevant to problems of compressible turbulence are simulated,including one-dimensional shock/entropy wave interaction,two-dimensional decaying isotropic turbulence,and two-dimensional temporal mixing layers.Numerical results indicate that higher numerical accuracy can be achieved on the same number of degrees of freedom with DG than high order finite difference schemes.Furthermore,shocks are also well captured using the localized artificial diffusivity method.The results in this work can provide useful guidance for further applications of DG to direct and large eddy simulation of compressible turbulent flows.展开更多
基金Supported by the National Science Foundation for Post-doctoral Scientists of China(20100481141,201104567)the Natural Science Foundation of Jiangsu Province(BK2011723)the Planned Projects for Postdoctoral Research Foundation of Jiangsu Province(0902001C)~~
文摘A hybrid central-upwind scheme is proposed. Two sub-schemes, the central difference scheme and the Roets flux difference splitting scheme, are hybridized by means of a binary sensor function. In order to examine the capability of the proposed hybrid scheme in computing compressible turbulent flow around a curved surface body, especially the flow involving shock wave, three typical eases are investigated by using detached-eddy simulation technique. Numerical results show good agreements with the experimental measurements. The present hybrid scheme can be applied to simulating the compressible flow around a curved surface body involving shock wave and turbulence.
基金Supported by the National Natural Science Foundation of China （50606026, 50736006）.
文摘The second-order moment combustion model, proposed by the authors is validated using the direct numerical simulation （DNS） of incompressible turbulent reacting channel flows. The instantaneous DNS results show the near-wall strip structures of concentration and temperature fluctuations. The DNS statistical results give the budget of the terms in the correlation equations, showing that the production and dissipation terms are most important. The DNS statistical data are used to validate the closure model in RANS second-order moment （SOM） combustion model. It is found that the simulated diffusion and production terms are in agreement with the DNS data in most flow regions, except in the near-wall region, where the near-wall modification should be made, and the closure model for the dissipation term needs further improvement. The algebraic second-order moment （ASOM） combustion model is well validated by DNS.
文摘This paper describes the design of a new kind of miniature abrading sphere, which is magnetically mounted inside a spherical gap and set in rotation pneumatically with air. Large eddy simulation is performed in conjunction with the compressible Smagorinsky model. Minimal temperature variation allows for the assumption of adiabatic walls. Fluid-solid interaction is modeled using the law of the wall for compressible turbulent flow. A parametric study is done to determine optimal geometric layout while taking physical restrictions into account. The resulting optimal configuration is then examined in detail in order to determine demands to be met by the computerized control of the magnetic bearing as well as to quantify the force available to the abrasion process. Finally, a mathematical relation is given that determines available abrasion force depending on standard volumetric flow rate and rotation frequency. The findings presented here provide a basis for further development of smaller versions of the tool.
基金supported by the National Basic Research Program of China(Grant No.2009CB724104)
文摘In this paper,the discontinuous Galerkin(DG)method combined with localized artificial diffusivity is investigated in the context of numerical simulation of broadband compressible turbulent flows with shocks for under-resolved cases.Firstly,the spectral property of the DG method is analyzed using the approximate dispersion relation(ADR)method and compared with typical finite difference methods,which reveals quantitatively that significantly less grid points can be used with DG for comparable numerical error.Then several typical test cases relevant to problems of compressible turbulence are simulated,including one-dimensional shock/entropy wave interaction,two-dimensional decaying isotropic turbulence,and two-dimensional temporal mixing layers.Numerical results indicate that higher numerical accuracy can be achieved on the same number of degrees of freedom with DG than high order finite difference schemes.Furthermore,shocks are also well captured using the localized artificial diffusivity method.The results in this work can provide useful guidance for further applications of DG to direct and large eddy simulation of compressible turbulent flows.
