沙坝地形上沿岸流不稳定运动模式变化特性

发布时间：2018-02-26 23:15

本文关键词： 沙坝沿岸流不稳定运动双峰速度剖面不稳定模式　出处：《水科学进展》2016年03期 　论文类型：期刊论文

【摘要】：为研究沙坝地形上沿岸流不稳定运动特征模式变化特性,建立了考虑底摩擦影响的不稳定模型,并用该模型计算了两种沙坝地形(坡度分别为1∶40和1∶100)上的不稳定特征模式,这些模式内容包括不稳定运动波长、传播速度、不稳定增长率和扰动速度场。将这些结果与忽略底摩擦计算结果进行了比较,分析了底摩擦对不稳定特征模式的影响。上述研究表明沙坝地形上不稳定运动传播速度约为时均沿岸流最大值的0.71~0.79;1∶40沙坝地形上产生不稳定运动所用的时间比1∶100地形上更短;底部摩擦可以很大程度上抑制沿岸流不稳定运动的产生;一般观测到的(准)韵律形、新月形沙坝都在后剪切区(紧邻时均沿岸流最大值向海方向区域)产生;不稳定运动在沙坝处运动最强,并且坡度越缓,不稳定运动沿岸方向波长越长。
[Abstract]:In order to study the characteristics of the unstable motion pattern of the coastal current on the sand dam topography, an unstable model considering the effect of bottom friction is established, and the unstable characteristic models of two kinds of sand dam topography (the slope is 1:40 and 1: 100) are calculated by using the model. These models include the wavelength of unstable motion, propagation velocity, unstable growth rate and disturbance velocity field. These results are compared with those calculated by neglecting the bottom friction. The influence of bottom friction on the unstable characteristic model is analyzed. The results show that the time taken to generate unstable motion on the topography of sand dam is less than that on 1: 100 terrain, which is about 0.71g 0.79-1: 40 of the maximum velocity of the unstable motion on the sand dam topography. The bottom friction can restrain the unstable motion of the coastal current to a large extent, and the (quasi-) rhythm and crescent sandbars are observed in the post-shear zone (adjacent to the area where the maximum value of the mean-coastal current flows to the sea). The unstable motion is the strongest in the sand dam, and the slower the slope, the longer the wavelength along the coast of the unstable motion.
【作者单位】：天津大学水利工程安全与仿真国家重点实验室;太原理工大学水利科学与工程学院;
【基金】：水利工程安全与仿真国家重点实验室开放基金资助项目(HESS-1406) 中国博士后科学基金资助项目(2013M541179)~~
【分类号】：TV139.2

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