Reynolds推出了Reynolds方程以来,人们花费大量精力研究方程的封闭性。Taylor首先引入相关概念并提出各态历经假说。Prandtl提出著名的混合长度理论:Karman给出混合长度的另外形式。周培源(Chou P Y)对各向同性湍流做了大量研究工作,获...Reynolds推出了Reynolds方程以来,人们花费大量精力研究方程的封闭性。Taylor首先引入相关概念并提出各态历经假说。Prandtl提出著名的混合长度理论:Karman给出混合长度的另外形式。周培源(Chou P Y)对各向同性湍流做了大量研究工作,获得了满意的结果。最近高歌用侧偏系综平均取代Reynolds平均。展开更多
由中国力学学会主办，中国力学学会和北京工业大学共同承办的“中国力学学会学术大会’2005”（Chinese Conference of Theoretical and Applied Mechanics-2005，CC—TAM’2005）于2005年8月26—28日在北京召开．大会主席由中国力学学...由中国力学学会主办，中国力学学会和北京工业大学共同承办的“中国力学学会学术大会’2005”（Chinese Conference of Theoretical and Applied Mechanics-2005，CC—TAM’2005）于2005年8月26—28日在北京召开．大会主席由中国力学学会理事长崔尔杰院士担任，副主席有程耿东、贺德馨、李家春、沈为平、苏先樾、王自强、吴有生、杨卫、卢振洋、张泽。展开更多
One mechanism by which laminar flow becomes turbulence is through the instability of vortex interaction.The nonlinear evolution of the interactions between the∧-vortex and the secondary closed vortex has been investi...One mechanism by which laminar flow becomes turbulence is through the instability of vortex interaction.The nonlinear evolution of the interactions between the∧-vortex and the secondary closed vortex has been investigated.This nonlinear instability process leads to some fundamental changes in the topology of flows.Experimental observations are presented here,showing the formation of a chain of ring-like vortices,which generate high frequency spikes on time traces in a transitional boundary layer.展开更多
This paper describes the evolution of surface capillary waves of deep water excited by gradually increasing the lateral external force at a single frequency. The vertical velocities of the water surface are measured b...This paper describes the evolution of surface capillary waves of deep water excited by gradually increasing the lateral external force at a single frequency. The vertical velocities of the water surface are measured by using a Polytec Laser Vibrometer with a thin layer of aluminium powder scattering on the surface to reflect the laser beam. Nonlinear interaction processes result in a stationary Fourier spectrum of the vertical surface velocities （the same as the surface elevation）, i.e. Iω -ω^-3-5. The observed spectrum can be interpreted as a wave-turbulent Kolmogorov spectrum for the case of ‘narrowband pumping＇ for a direct cascade of energy. Correlation dimension analysis of the whole development process reveals four distinct stages during the wave structure development and identifies the wave turbulence stage.展开更多
文摘Reynolds推出了Reynolds方程以来,人们花费大量精力研究方程的封闭性。Taylor首先引入相关概念并提出各态历经假说。Prandtl提出著名的混合长度理论:Karman给出混合长度的另外形式。周培源(Chou P Y)对各向同性湍流做了大量研究工作,获得了满意的结果。最近高歌用侧偏系综平均取代Reynolds平均。
文摘由中国力学学会主办，中国力学学会和北京工业大学共同承办的“中国力学学会学术大会’2005”（Chinese Conference of Theoretical and Applied Mechanics-2005，CC—TAM’2005）于2005年8月26—28日在北京召开．大会主席由中国力学学会理事长崔尔杰院士担任，副主席有程耿东、贺德馨、李家春、沈为平、苏先樾、王自强、吴有生、杨卫、卢振洋、张泽。
基金Supported by the National Natural Science Foundation of China under Grant No.19972034,and in part by the Isaac Newton Institute for Mathematical Sciences,University of Cambridge.
文摘One mechanism by which laminar flow becomes turbulence is through the instability of vortex interaction.The nonlinear evolution of the interactions between the∧-vortex and the secondary closed vortex has been investigated.This nonlinear instability process leads to some fundamental changes in the topology of flows.Experimental observations are presented here,showing the formation of a chain of ring-like vortices,which generate high frequency spikes on time traces in a transitional boundary layer.
基金Project supported by the National Natural Science Foundation of China (Grant No 10087101)the National Science Fund for Distinguished Young Scholars (Grant No 10525208)
文摘This paper describes the evolution of surface capillary waves of deep water excited by gradually increasing the lateral external force at a single frequency. The vertical velocities of the water surface are measured by using a Polytec Laser Vibrometer with a thin layer of aluminium powder scattering on the surface to reflect the laser beam. Nonlinear interaction processes result in a stationary Fourier spectrum of the vertical surface velocities （the same as the surface elevation）, i.e. Iω -ω^-3-5. The observed spectrum can be interpreted as a wave-turbulent Kolmogorov spectrum for the case of ‘narrowband pumping＇ for a direct cascade of energy. Correlation dimension analysis of the whole development process reveals four distinct stages during the wave structure development and identifies the wave turbulence stage.
