The present work is intended to simulate, in a rotating annulus of stratified liquid, the me-chanical effect of the Xizang (Tibetan) Plateau on the zonal circulation. The main featuresof three flow patterns around the...The present work is intended to simulate, in a rotating annulus of stratified liquid, the me-chanical effect of the Xizang (Tibetan) Plateau on the zonal circulation. The main featuresof three flow patterns around the plateau for different Rossby number R and rotating Eulernumber E are analysed. and a division diagram of the flow pattern in (R, E) plane is given.It has been found that under the condition that similarity criterions R and E of the experimentalfluid are the same as those existing in the atmosphere for monthly mean states in spring, au-tumn and winter months, the experimental results are satisfied for the following weathersystems over the plateau and its vicinities: the low vortex, trough and shear line over thesoutheast part of the plateau, the tilted ridge over the northwest part of the plateau, the troughpatterns over the upstream and dewnstream of the plateau, the vertical circulation structure, thejets on both north and southeast sides of the plateau, and so on. This shows that the mechanicaleffect of the Tibetan Plateau on the general circulation over East Asia deserves close atten-tion.展开更多
The mode-2 internal solitary wave(ISW)propagating independently in the stratified ocean is a high-mode internal wave(IW),and its complex wave-flow field will cause the harm to the safe operation of marine engineering ...The mode-2 internal solitary wave(ISW)propagating independently in the stratified ocean is a high-mode internal wave(IW),and its complex wave-flow field will cause the harm to the safe operation of marine engineering structures.In this paper,a fluid environment with a continuous density pycnocline was prepared in a large experimental stratified fluid flume.Based on the principle of ISWs generated by the fluid gravity collapse,a physical experimental method for exciting the“oval”mode-2 ISW solitons by bidirectional fluid gravity collapse in a continuous density pycnocline was proposed.The experimental results showed that the evolution of the upper and lower double vortices near the center of pycnocline is a special generation mechanism of the generation process of mode-2 ISW generated by the gravity collapse of the stratified fluid.The number of generated mode-2 ISW internal solitons depends on the geometric size of fluid gravity collapse region and the geometric thickness ratio of the upper and lower layers of the fluid.The wave evolution process,wave-flow structure,wave-flow characteristics of the“oval”mode-2 ISW in the continuous density pycnocline and its stratified environment effect were obtained.The results showed that the wave speed of the mode-2 ISW increases with the increasing wave amplitude,and the wavelength increases first and then decreases with the increasing wave amplitude.Under the experimental conditions with same wave amplitude,the increase of the thickness ratio of the upper and lower layers of the fluid,the density difference and the thickness of the middle fluid layer would lead to the increase of the wavelength and wave speed of the mode-2 ISW.The velocity range of the mode-2 ISW is positively correlated with the wave amplitude.The increase of the thickness ratio of the upper and lower fluid layers,the density difference and the thickness of the middle fluid layer will lead to the enhancement of the horizontal and vertical flow field of the mode-2 ISW.展开更多
文摘The present work is intended to simulate, in a rotating annulus of stratified liquid, the me-chanical effect of the Xizang (Tibetan) Plateau on the zonal circulation. The main featuresof three flow patterns around the plateau for different Rossby number R and rotating Eulernumber E are analysed. and a division diagram of the flow pattern in (R, E) plane is given.It has been found that under the condition that similarity criterions R and E of the experimentalfluid are the same as those existing in the atmosphere for monthly mean states in spring, au-tumn and winter months, the experimental results are satisfied for the following weathersystems over the plateau and its vicinities: the low vortex, trough and shear line over thesoutheast part of the plateau, the tilted ridge over the northwest part of the plateau, the troughpatterns over the upstream and dewnstream of the plateau, the vertical circulation structure, thejets on both north and southeast sides of the plateau, and so on. This shows that the mechanicaleffect of the Tibetan Plateau on the general circulation over East Asia deserves close atten-tion.
基金supported by the National Natural Science Foundation of China(Grant No.12472247)supported by the Natural Science Foundation of Hunan Province(Grant No.2025JJ60027)+1 种基金the Innovation Research Foundation of National University of Defense Technology(Grant No.ZK24-51)the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC3005).
文摘The mode-2 internal solitary wave(ISW)propagating independently in the stratified ocean is a high-mode internal wave(IW),and its complex wave-flow field will cause the harm to the safe operation of marine engineering structures.In this paper,a fluid environment with a continuous density pycnocline was prepared in a large experimental stratified fluid flume.Based on the principle of ISWs generated by the fluid gravity collapse,a physical experimental method for exciting the“oval”mode-2 ISW solitons by bidirectional fluid gravity collapse in a continuous density pycnocline was proposed.The experimental results showed that the evolution of the upper and lower double vortices near the center of pycnocline is a special generation mechanism of the generation process of mode-2 ISW generated by the gravity collapse of the stratified fluid.The number of generated mode-2 ISW internal solitons depends on the geometric size of fluid gravity collapse region and the geometric thickness ratio of the upper and lower layers of the fluid.The wave evolution process,wave-flow structure,wave-flow characteristics of the“oval”mode-2 ISW in the continuous density pycnocline and its stratified environment effect were obtained.The results showed that the wave speed of the mode-2 ISW increases with the increasing wave amplitude,and the wavelength increases first and then decreases with the increasing wave amplitude.Under the experimental conditions with same wave amplitude,the increase of the thickness ratio of the upper and lower layers of the fluid,the density difference and the thickness of the middle fluid layer would lead to the increase of the wavelength and wave speed of the mode-2 ISW.The velocity range of the mode-2 ISW is positively correlated with the wave amplitude.The increase of the thickness ratio of the upper and lower fluid layers,the density difference and the thickness of the middle fluid layer will lead to the enhancement of the horizontal and vertical flow field of the mode-2 ISW.
