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Stochastic modeling of subgrid-scale effects on particle motion in forced isotropic turbulence

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Chinese Journal of Chemical Engineering 2019年第12期27卷 2884-2891页

作者： Haoshu Shen YuxinWu Minmin Zhou Hai Zhang Guangxi Yue Key Laboratory for Thermal Science and Power Engineering of Ministry Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Institute for Clean and Secure Energy Department of Chemical EngineeringUniversity of UtahSalt Lake City 84112United States

The subgrid-scale effects on particle motion were investigated in forced isotropic turbulence by DNS and priorLES *** the DNS field,the importance of Kolmogorov scaling to preferential accumulation was validated by comparing the radial distribution functions under various particle Stokes *** prior-LES fields were generated by filtering the DNS *** subgrid-scale Stokes number(StSGS)is a useful tool for determining the effects of subgrid-scale eddies on particle *** subgrid-scale eddies tend to accumulate particles with StSGSb 1 and disperse particles with 1 b StSGSb *** particles with StSGS?1,the effects of subgrid-scale eddies on particle motion can be *** order to restore the subgrid-scale effects,the Langevin-type stochastic model with optimized parameters was adopted in this *** model is effective for the particles with StSGS N 1 while has an adverse impact on the particles with StSGSb *** results show that the Langevin-type stochastic model tends to smooth the particle distribution in the isotropic turbulence.

关键词： Particle dispersion subgrid-scale modeling Forced isotropic turbulence Stokes number

An improved dynamic subgrid-scale model and its application to large eddy simulation of rotating channel flows

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Science China(Physics,Mechanics & Astronomy) 2004年第4期47卷 463-476页

作者： LIU Nansheng LU Xiyun ZHUANG Lixian Department of Mechanics and Mechanical Engineering University of Science and Technology of ChinaHefei 230026 China Department of Mechanics and Mechanical Engineering University of Science and Technology of ChinaHefei 230026 China Department of Mechanics and Mechanical Engineering University of Science and Technology of ChinaHefei 230026 China

A new dynamic subgrid-scale (SGS) model, which is proved to satisfy the principle of asymptotic material frame indifference (AMFI) for rotating turbulence, is proposed based on physical and mathematical analysis. Comparison with direct numerical simulation (DNS) results verifies that the new SGS model is effective for large eddy simulation (LES) on rotating turbulent flow. The SGS model is then applied to the LES of the spanwise rotating turbulent channel flow to investigate the rotation effect on turbulence characteristics, budget terms in the transport equations of resolved Reynolds stresses, and flow structures near the wall regions of the rotating channel.

关键词： large eddy simulation (LES), dynamic subgrid-scale (SGS) model, rotating turbulent channel flow,asymptotic material frame indifference (AMFI).

A dynamic subgrid-scale model for the large eddy simulation of stratified flow

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Science China Mathematics 2000年第4期43卷 391-399页

作者：刘宁宇陆夕云庄礼贤 Department of Modem Mechanics University of Science and Technology of China Hefei 230026 China

A new dynamic subgrid-scale (SGS) model, including subgrid turbulent stress and heat flux models for stratified shear flow is proposed by using Yoshizawa’ s eddy viscosity model as a base model. Based on our calculated results, the dynamic subgrid-scale model developed here is effective for the large eddy simulation (LES) of stratified turbulent channel flows. The new SGS model is then applied to the large eddy simulation of stratified turbulent channel flow under gravity to investigate the coupled shear and buoyancy effects on the near-wall turbulent statistics and the turbulent heat transfer at different Richardson numbers. The critical Richardson number predicted by the present calculation is in good agreement with the value of theoretical analysis.

关键词： large eddy simulation (LES) subgrid-scale model (SGS) stratified turbulence heat transfer.

Large-eddy simulations of the Richtmyer-Meshkov instability of rectangular interfaces accelerated by shock waves

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Science China(Physics,Mechanics & Astronomy) 2010年第12期53卷 905-914页

作者： WANG Tao,BAI JingSong,LI Ping & LIU Kun Institute of Fluid Physics,China Academy of Engineering Physics,Mianyang 621900,China China Academy of Engineering Physics Institute of Fluid Physics Mianyang China (GRID:grid.249079.1) (ISNI:***)

A parallel algorithm and code MVFT(multi-viscous-fluid and turbulence) of large-eddy simulation(LES) is developed from our MVPPM(multi-viscous-fluid piecewise parabolic method),and performed to solve the multi compressible Navier-Stokes(N-S) *** effect of the unresolved subgrid-scale(SGS) motions on the large scales is represented by different SGS stress models in LES.A Richtmyer-Meshkov instability experiment of the evolution of a rectangular block of SF6,which occupies half of the height of the shock tube test section,following the interaction with a planar shock wave,is numerically and exhaustively simulated by this *** comparison between experimental and simulated images of the evolving SF6 block shows that they are *** numerical simulations reproduce the complex developing process of SF6 block,which grows *** geometric quantities that characterize the extents of SF6 block are also compared in detail between numerical simulations and experiment with good agreements between them,a quantitative demonstration of the developing law of SF6 *** is an evident discrepancy between the three numerical simulations for the maximum position of the right edge of block at the late stage,because the right interface grows complicated and the dissipation is different for different SGS *** SGS turbulent dissipation,molecular viscosity dissipation and SGS turbulent kinetic energy have been studied and *** have a similar distribution to the large eddy *** SGS turbulent dissipation is much greater than the molecular viscosity dissipation;the SGS turbulent dissipation of Vreman model is smaller than the Smagorinsky *** general,the simulated results of Vreman SGS model are better compared with the dynamic viscosity and Smagorinsky SGS *** vorticity and circulation deposition on the block interface have also been investigated.

关键词： large-eddy simulation Navier-Stokes equations subgrid-scale Richtmyer-Meshkov instability turbulent dissipation turbulent kinetic energy circulation deposition

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Rotation effect on near-wall turbulence statistics and flow structures

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Science China(Physics,Mechanics & Astronomy) 2005年第2期48卷 211-227页

作者： LIU Nansheng LU Xiyun ZHUANG Lixian Department of Mechanics and Mechanical Engineering University of Science and Technology of China Hefei 230026 China Department of Mechanics and Mechanical Engineering University of Science and Technology of China Hefei 230026 China Department of Mechanics and Mechanical Engineering University of Science and Technology of China Hefei 230026 China

Large eddy simulation (LES) of turbulent flow through an axially rotating pipe, coupled with nonlinear dynamic subgrid-scale (SGS) model, is carried out to investigate rotation effect on the near-wall turbulence characteristics and flow structures. In the rotating turbulent pipe flow, it is found that the tendency towards a relaminarized flow appears and the axial velocity fluctuation is suppressed; however, the azimuthal fluctuation is enhanced due to the presence of the pipe wall rotation. The joint probability density function (joint PDF) of the velocity fluctuations and the probability density function (PDF) of the helicity fluctuation are analyzed in detail. It is revealed that the resolved Reynolds stress and helicity fluctuation in the wall region are closely related to the correlation between the velocity and vorticity fluctuations and affected significantly by the rotation-induced azimuthal mean flow. Further, the budgets of resolved Reynolds stresses indicate that the rotation effect is responsible for the more active turbulent energy redistribution and the production of the azimuthal turbulence fluctuation. The near-wall inclined streaky structures with respect to the axial direction are ascribed to the spiral motion of the fluid induced by the rotating pipe. The turbulence characteristics revealed in this study are of great help for the understanding of physical fundamentals in the rotating turbulent flows and for the development of reliable turbulence model.

关键词： large eddy simulation (LES), dynamic subgrid-scale (SGS) model, rotating turbulent flow, coherent structures.

A novel dynamic coherent eddy model and its application to LES of a turbulent jet with free surface

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Science China(Physics,Mechanics & Astronomy) 2010年第9期53卷 1671-1680页

作者： LU Jun,TANG HongWu,WANG LingLing & PENG Feng College of water conservancy of hydro-power engineering,Hohai University,Nanjing 210098,China Hohai University College of water conservancy of hydro-power engineering Nanjing China (GRID:grid.257065.3) (ISNI:***)

We has developed a novel dynamic coherent eddy model,in which the coherent structure-Q criterion introduced by Hunt et al(1988)-is taken into account in the subgrid-scale turbulent viscosity based on the eddy viscosity *** proposed method is to combine the resolved-scale velocity-gradient tensor in the classical Smagorinsky model with Q criterion weighted.A kind of dynamic procedure which was averaged in a general process at temporal direction based on the autocorrelations of the characteristic resolved scales of turbulence was taken for the coefficient of subgrid *** model is implemented in the σ-coordinate and the filtered Navier-Stokes equations are solved by the operator splitting *** validation was explored to 2-D turbulent slot jet both in ambient environment and in regular *** prediction of the present model was compared with the experiment data,including the averaged velocity profiles,the velocity fluctuations and the Reynolds *** model performance is shown to be satisfactory.

关键词： LES subgrid-scale modeling σ-coordinate turbulent jet

LES of rotating film-cooling performance in a 1-1/2 turbine stage

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Propulsion and Power Research 2019年第2期8卷 85-107页

作者： Nabeel Al-Zurfi Adel Nasser Mechanical Engineering Department Faculty of EngineeringUniversity of KufaNajafIraq School of Mechanical Aerospace and Civil EngineeringThe University of ManchesterManchesterM139PLUK

The large eddy simulation method was employed to investigate the film-cooling performance in a low-speed rotor blade of a 1-1/2 turbine *** rotor blade height and axial chord length were 99 mm and 124.3 mm,*** rows of film holes were placed on the rotor blade surface,one each on the pressure and suction *** row had three cylindrical film holes with a diameter of 4 mm and a tangential injection angle of 28°on the pressure side and 361 on the suction *** Reynolds number was fixed at Re=1.92×10^(5)and the coolant-to-mainstream density ratio(DR)was about *** were carried out for three different rotating speeds of 1800,2100,and 2400 rpm with the blowing ratio(BR)varying from 0.3 to *** commercial CFD code STAR-CCM+was used to run the simulations using the WALE subgrid-scale model for modelling the *** results show that on the pressure side,the film coverage and filmcooling effectiveness decrease with increasing rotation number(Ro)and increase with increasing blowing ratio(BR).A higher Ro and lower BR result in a stronger film *** film injection with higher BR produces better film *** film deflects centrifugally where the deflection becomes greater with increasing *** the suction side,the film coverage and film-cooling effectiveness increase with increasing either Ro or BR and a centripetal deflection of the film is *** deflection of the film path could be amplified by either increasing the Ro at a constant BR or decreasing the BR at a constant *** the rotation weakens the film deflection towards the hub on the suction ***,it was found that both rotation number and blowing ratio play significant roles in determining the film-cooling effectiveness distributions of the rotor blade surface.

关键词： Rotor blade Large eddy simulation Film-cooling effectiveness Turbulence Rotation subgrid-scale