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Large-eddy simulations and vortex structures of turbulent jets in crossflow

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science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 118-132页

作者： guan hui1,2 & wu chuijie2.1 School of Mechanical and Power Engineering,East china university of science and technology,Shanghai 200237,china 2 research center for fluid dynamics,pla university of science and technology,nanjing 2.1101,china 1. School of Mechanical and Power Engineering East China University of Science and Technology Shanghai 200237 China 2. research center for fluid dynamics PLA University of Science and Technology Nanjing 211101 China

Using the method of large-eddy simulation, the 3-dimensional turbulent jets in crossflow with stream-wise and transverse arrangements of nozzle are simulated, emphasizing on the dynamical process of generation and evolution of vortex structures in these flows. The results show that the basic vortex structures in literatures, such as the counter-rotating vortex pair, leading-edge vortices, lee-side vortices, hanging vortices, kidney vortices and anti-kidney vortices, are not independent physical substances, but local structures of the basic vortex structure of turbulent jets in crossflow-the 3-D stretching vortex rings originating from the orifice of the nozzle, which is discovered in this study. Therefore, the most important large-scale structures of turbulent jets in crossflow are unified to the 3-D vortex rings which stretch and twist in stream-wise and swing in transverse directions. We also found that the shedding frequencies of vortex rings are much lower than the one corresponding to the appearance of leading-edge and lee-side vortices in the turbulent jets.

关键词： turbulent jet in crossflow coherent structure large-eddy simulation

A method of constructing a database-free optimal dynamical system and a global optimal dynamical system

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science china(Physics,Mechanics & Astronomy) 2008年第7期51卷 905-915页

作者： wu chuijie1? & WANG Liang2.1 State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian university of technology, Dalian 116024, china 2 research center for fluid dynamics, School of science, pla university of science and technology, nanjing 2.1101, china 1. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China 2. research center for fluid dynamics School of Science PLA University of Science and Technology Nanjing 211101 China

In this paper, to overcome the drawbacks of POT which minimize the reminder, not only the optimal functional with minimal residual is put forward, but also the method of global optimization is used. Under the condition of large reminder, the optimal bases can also be obtained through the method of POTres without the approaching of initial conditions. In addition, compared with local optimization, the advantage of global optimization is remarkable. On the one hand, we can expect that the dynamical system based on the global optimal bases will include more information than the ones based on the local optimal bases, since the global optimal bases are much more precise than the local optimal bases. On the other hand, from the point of view of error, the global optimal bases are independent of the choice of the object functional and the initial bases.

关键词： dynamical system residual global optimization

Large-eddy simulation of formation of three-dimensional aeolian sand ripples in a turbulent field

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science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 945-960页

作者： wu chuijie1,WANG Ming2 & WANG Liang3 1 State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian university of technology,Dalian 116024,china 2 Yellow River Institute of Hydraulic research,Zhengzhou 450003,china 3 research center for fluid dynamics,science School,pla university of science and technology,nanjing 2.1101,china State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China Yellow River Institute of Hydraulic research Zhengzhou 450003 China research center for fluid dynamics Science School PLA University of Science and Technology Nanjing 211101 China

With the method of large-eddy simulation,the equation of spherule motion and the method of immersed boundary condition,numerical simulations of three-dimen-sional turbulent aeolian motion and the formation of sand ripples under three-di-mensional turbulent wind and the mutual actions of saltation and creeping motion were carried out. The resulting sand ripples have the form that is flat on the upwind side and steep on the leeward,which is identical to the sand ripples in nature. We also realized the self-restoration process of three-dimensional sand ripples,which shows the correctness of the method of numerical simulation and the models of saltation and creeping. Finally,We analyzed the influence of sand ripples on the three-dimensional turbulent wind field,and found that due to the appearance and development of sand ripples,in the normal direction of ground there exists stronger energy exchange,and moreover,there is close correspondence between the forms of sand ripples and the vorticity close to the ground surface.

关键词： large-eddy simulation equation of spherule motion sand ripples saltation creep

Numerical simulations of self-propelled swimming of 3D bionic fish school

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science china(Technological sciences) 2009年第3期52卷 658-669页

作者： wu chuijie1 & WANG Liang2.1 State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian university of technology, Dalian 116024, china 2 research center for fluid dynamics, People’s Liberation Army university of science and technology, nanjing 2.1101, china State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China research center for fluid dynamics People’s Liberation Army University of Science and Technology Nanjing 211101 China

Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package produced for 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis- cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements.

关键词： adaptive multi-grid immersed boundary method self-propelled swimming fish school 3D bionic fish

Large-Eddy Simulations of turbulent flows with lattice Boltzmann dynamics and dynamical system sub-grid models

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中国科学:技术科学 2010年第3期 335-335页

In this paper,two sub-grid scale (SGS) models are introduced into the Lattice Boltzmann Method (LBM),i.e.,the dynamics SGS model and the dynamical system SGS model,and applied to numerically solving three-dimensional high Re turbulent cavity *** are compared with those obtained from the Smagorinsky model and direct numerical simulation for the same *** is shown that the method with LBM dynamics SGS model has advantages of fast computation speed,suitable to simulate high Re turbulent *** addition,it can capture detailed fine structures of turbulent flow *** method with LBM dynamical system SGS model dose not contain any adjustable parameters,and can be used in simulations of various complicated turbulent flows to obtain correct information of sub-grid flow field,such as the backscatter of energy transportation between large and small scales.A new average method of eliminating the inherent unphysical oscillation of LBM is also given in the paper.

关键词： Large-Eddy Simulation Lattice Boltzmann Method dynamics sub-grid scale model dynamical system sub-grid scale model parallel computation

NUMERICAL SIMULATION OF THREE-DIMENSIONAL SELF-PROPELLED SWIMMING OF BIONIC FISH SCHOOL

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NUMERICAL SIMULATION OF THREE-DIMENSIONAL SELF-PROPELLED SWI...

research on the optimal dynamical systems of three-dimensional Navier-Stokes equations based on weighted residual

庆祝中国力学学会成立50周年暨中国力学学会学术大会’2007

作者： wu chuijie~(*,1)) WANG Liang~(*,**) *(Institute of fluid Mechanics,Hohai university,nanjing 210098,china) **(research center for fluid dynamics,pla university of science and technology,nanjing 2.1101,china)

Three dimensional numerical simulations of self-propelled swimming of bionic fish and fish school in a viscous flow in a tank are *** swimming rule and the profile of 3D fish from previous experimental measurements of... 详细信息

关键词： adaptive multigrid immersed boundary method self-propelled swimming fish school 3D bionic fish

来源： cnki会议评论

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science china(Physics,Mechanics & Astronomy) 2016年第4期59卷 78-85页

作者： NaiFu Peng hui guan chuijie wu State Key Laboratory of Structural Analysis for Industrial Equipment School of Aeronautics and AstronauticsDalian University of Technology State Key Laboratory for Turbulence and Complex Systems Center for Applied Physics and TechnologyCollege of Engineering Peking University College of Meteorology and Oceanography PLA University of Science and Technology

In this paper, the theory of constructing optimal dynamical systems based on weighted residual presented by wu & Sha is applied to three-dimensional Navier-Stokes equations, and the optimal dynamical system modeling equations are derived. Then the multiscale global optimization method based on coarse graining analysis is presented, by which a set of approximate global optimal bases is directly obtained from Navier-Stokes equations and the construction of optimal dynamical systems is realized. The optimal bases show good properties, such as showing the physical properties of complex flows and the turbulent vortex structures, being intrinsic to real physical problem and dynamical systems, and having scaling symmetry in mathematics, etc.. In conclusion, using fewer terms of optimal bases will approach the exact solutions of Navier-Stokes equations, and the dynamical systems based on them show the most optimal behavior.

关键词： optimal dynamical systems weighted residual three-dimensional Navier-Stokes equations vortex structures

Optimal dynamical systems of Navier-Stokes equations based on generalized helical-wave bases and the fundamental elements of turbulence

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science china(Physics,Mechanics & Astronomy) 2016年第11期59卷 61-69页

In this paper, we present the theory of constructing optimal generalized helical-wave coupling dynamical systems. Applying the helical-wave decomposition method to Navier-Stokes equations, we derive a pair of coupling dynamical systems based on optimal generalized helical-wave bases. Then with the method of multi-scale global optimization based on coarse graining analysis, a set of global optimal generalized helical-wave bases is obtained. Optimal generalized helical-wave bases retain the good properties of classical helical-wave bases. Moreover, they are optimal for the dynamical systems of Navier-Stokes equations, and suitable for complex physical and geometric boundary conditions. Then we find that the optimal generalized helical-wave vortexes fitted by a finite number of optimal generalized helical-wave bases can be used as the fundamental elements of turbulence, and have important significance for studying physical properties of complex flows and turbulent vortex structures in a deeper level.

关键词： optimal dynamical systems helical-wave decomposition fundamental elements of turbulence vortex structures

A study of a three-dimensional self-propelled flying bird with flapping wings

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science china(Physics,Mechanics & Astronomy) 2015年第9期58卷 52-67页

作者： ZHU LinLin guan hui wu chuijie State Key Laboratory of Structural Analysis for Industrial Equipment School of Aeronautics and Astronautics Dalian University of Technology College of Meteorology and Oceanography PLA University of Science and Technology

In this paper, a study of a three-dimensional(3D) self-propelled bionic flying bird in a viscous flow is carried out. This bionic bird is propelled and lifted through flapping and rotating wings, and better flying can be achieved by adjusting the flapping and rotation motion of wings. In this study, we found that the bird can fly faster forward and upward with appropriate center of rotation and oscillation without more energy consumption and have perfect flight performance at a certain angle of attack by adjusting the center of oscillation. The study utilizes a 3D computational fluid dynamics package which constitutes combined immersed boundary method and the volume of fluid method. In addition, it includes adaptive multigrid finite volume method and control strategy of swimming and flying.

关键词： self-propelled bird flying numerical simulation three-dimensional