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NUMERICAL SIMULATION OF turbulent spotS IN INCLINED OPEN-CHANNEL FLOW

Journal of Hydrodynamics 2005年第2期17卷 179-185页

作者： ZHANGLi TANGDeng-bin CollegeofAerospaceEngineering NanjingUniversityofAeronauticsandAstronauticsNanjing210016China

The generation and evolution of turbulent spots in the open-channel flow are simulated numerically by using the Navier-Stokes equations. An effective numerical method with high accuracy and high resolution is developed. The fourth-order time splitting methods with high accuracy is proposed. Three-dimensional coupling difference methods are presented for the spatial discretization of the Poisson equation of pressure and Hemholtz equations of velocity, therefore, the fourth-order three-dimensional coupling central difference schemes are constituted. The fourth-order explicit upwind-biased compact difference schemes are designed to overcome the difficulty for the general higher-order central difference scheme which is inadaptable in the boundary neighborhood. The iterative algorithm and overall time marching is used to enhance efficiency. The method is applied in the numerical simulation of turbulent spots at various complex boundary conditions and flow domains. The generation and the developing process of turbulent spots are given, and the basic characteristics of turbulent spots are shown by simulating the evolution of the wall pulse in inclined open-channel flow.

关键词： turbulent spot Navier-Stokes equation numerical simulation three-dimensional coupling difference scheme wall pulse

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STUDY ON turbulent spotS IN PLANE COUETTE FLOW

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Transactions of Nanjing University of Aeronautics and Astronautics 2007年第3期24卷 211-217页

作者：陈林唐登斌南京航空航天大学航空宇航学院

turbulent spots play a key role in the formation of the turbulence and the transition. The generation and evolution of turbulent spots using the wall impulse model in the plane Couette flow are studied by direct numerical simulation of Navier-Stokes equations. A group of three-dimensional coupling compact difference schemes with high accuracy and high resolution is used in the numerical calculation. The important characteristics of turbulent spots based on the results of examples are analyzed, including the formation of random pulse, the generation of Reynolds stress, the growth of disturbance amplitude, and the continuous change of spot shape, especially the complex evolution process of the streamwise vortices. Computational results confirm that basic properties of turbulent spots in the laminar flow are similar to those in the turbulent flow.

关键词： turbulent spot streamwise vortex Couette flow direct numerical simulation

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Computational Study of Flat Plate Boundary Layer Transition Induced by Passing Wakes

Computational Study of Flat Plate Boundary Layer Transition ...

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2003’全国流体力学青年研讨会

作者： Xiaohua Wu Flow Physics and Computation Division Department of Mechanical Engineering Stanford University,Stanford,CA 94305-3030

＜正＞ The interaction between an initially laminar boundary layer developing spatially on a flat plate and migrating freestream turbulent wakes has been simulated. The momentum thickness Reynolds number Ree evolves from 80 to 1120. Mean and second-order statistics downstream of Ree = 800 agree with existing canonical turbulent flat plate boundary layer data. Growth of turbulent spot was found to be the dominant feature in the late stage of transition between Ree = 200 and 600. However, dynamics of the spot growth is not as clear as its kinematics. Inlet disturbances inside the boundary layer evolve into streaky structures in the early stage of transition, though the mechanism requires further clarification. Breakdown of the laminar flow and generation of young turbulent spots around Ree = 200 is caused by localized freestream forcing on the streaks from the Kelvin-Helmholtz instability. The transitioned flow downstream of Ree = 800 may serve as a platform for structural investigations on flat plate boundray layers.

关键词： Wake boundary layer transition turbulent spot breakdown.

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