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首页> 外文会议>25th International Conference on Offshore Mechanics and Arctic Engineering 2006(OMAE2006) vol.2: Ocean Engineering; Polar and Arctic Sciences and Technology >The Preliminary Study on Comparison of Velocity Distribution Models Under the Same Roughness Length
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The Preliminary Study on Comparison of Velocity Distribution Models Under the Same Roughness Length

机译：相同粗糙度下速度分布模型比较的初步研究

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Previous studies pointed out that due to the acceleration or deceleration action of tide current, the flow structure deviates from traditional logarithmic law in estuary, coast or other near shore water. The tidal velocity distribution model was derived and compared with the traditional logarithmic model. It should be pointed out that the velocity data adopted have four layers within one meter above the bed, and the roughness length z_0 is different in the two models even in the same velocity profile. Because the fluctuation of roughness length z_0 is remarkable when determining by single velocity profile, some studies thought that the variation of roughness length was small between adjacent time when the change of topography was less obviously. Therefore, the measured data is divided into several sections by one day or a tidal cycle to fit the velocity profile of every section to obtain a roughness length z_0, i.e., the roughness length z_0 varies only after a day or a tidal cycle. The purpose of the paper is to expand the log-linear model to full depth by adding the surface boundary condition ∂u/∂z|_(z=D = 0 (D is water depth) and to discuss the difference when 6 points (bottom layer,0.2D,0.4D,0.6D, 0.8D, surface layer) velocity profile are fitted by logarithmic model, log-linear model, and extended log-linear model with the same roughness length z_0 in different time section, respectively. The calculated friction velocity and friction coefficient and their correlation are discussed. The results show that the log-linear model and the log-linear extend model are closer to the measure velocity profile than that of the logarithmic model.
机译：先前的研究指出，由于潮汐流的加速或减速作用，在河口，海岸或其他近岸水域中，水流结构与传统对数定律有所偏离。推导了潮汐速度分布模型，并将其与传统对数模型进行了比较。应该指出的是，所采用的速度数据在床层上方一米范围内有四层，并且即使在相同的速度剖面下，两个模型的粗糙度长度z_0也不同。由于通过单速度曲线确定时粗糙度长度z_0的波动非常明显，因此一些研究认为，在地形变化不太明显的情况下，相邻时间之间粗糙度长度的变化较小。因此，将测得的数据按一天或一个潮汐周期分成几个部分，以拟合每个部分的速度分布，以获得粗糙度长度z_0，即，粗糙度长度z_0仅在一天或一个潮汐周期之后才变化。本文的目的是通过添加表面边界条件∂u/∂z| _（z = D = 0（D为水深）来扩展对数线性模型，并讨论6点（通过对数模型，对数线性模型和扩展对数线性模型分别在不同时间段具有相同的粗糙度长度z_0来拟合底层（0.2D，0.4D，0.6D，0.6D，0.8D，表面层）速度分布。讨论了计算得到的摩擦速度和摩擦系数及其相关性，结果表明，对数线性模型和对数线性延伸模型比对数模型更接近测量速度轮廓。

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