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异重流在层结环境下的运动特性是海洋、大气等学科领域重要的研究主题之一.本研究在不同层结盐水中开展一系列实验,对突然释放型异重流在斜坡上的发展和演变特性进行了研究.非层结水体中异重流头部速度先迅速增大,而后基本不变减速幅度较小;而在层结水体中异重流头部速度先增大,之后明显减小,其发展主要分为加速阶段、减速阶段和分离阶段三个过程.异重流的运动特性可以用相对层结度S、雷诺数Re和理查德森数Ri0等无量纲参数描述.采用高速相机对异重流头部位置、头部速度和剖面速度等进行了分析.用激光粒子图像测速技术(PIV)得到异重流的速度场和涡度场,结果表明在异重流不同位置的涡度方向存在差异,上边界的正向开尔文-亥姆霍兹涡是产生卷吸的主要原因,下边界的负向涡度则由边界层引起.本文揭示了层结与非层结水体下异重流运动特性的不同影响机理和特性,结果可在河口盐水入侵、海底浊流发展等实际领域中得到应用.
The kinematic characteristics of gravity flow in stratified environment are one of the most important research topics in the field of ocean and atmosphere.In this study, a series of experiments were carried out in different stratified brine, and the development of sudden release-type gravity flow on the slope And non-gravity flow in non-stratified water bodies, the head velocity of non-gravity flow first increases rapidly and then decreases substantially, while the head velocity of heavy flow increases first in stratified water bodies, and then obviously And its development is divided into three stages of acceleration phase, deceleration phase and separation phase.The motion characteristics of gravity flow can be described by the dimensionless parameters of relative stratification S, Reynolds number Re and Richardson number Ri0. The high-speed camera was used to analyze the head position, head speed and section velocity of heavy flow, etc. Velocity field and vorticity field of heavy flow were obtained by Laser Particle Image Velocimetry (PIV) There are differences in the vorticity directions at the upper boundary, the positive Kelvin-Helmholtz vortex at the upper boundary is the main reason for entrainment, and the negative vorticity at the lower boundary is caused by the boundary layer. Extra-heavy flow of water under special movement The influence of different mechanisms and characteristics, results in estuarine saltwater intrusion, the actual area of the seabed turbidity development in the applications.