Measurement and modeling of bed shear stress under solitary waves
Measurement and modeling of bed shear stress under solitary waves
复制标题
孤立波下床层剪应力的测量和建模
DOI：
10.1016/j.coastaleng.2011.05.012
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
T. Baldock
中科院分区：
文献类型：
--
作者：
Jaya Kumar Seelam;P. Guard;T. Baldock
直接测量床剪切应力（使用剪切细胞装置）产生的非破碎孤立波。测量是在层流和过渡流（~ 104< Re< ~ 105）的光滑床上进行的。测量时，波高水深比（h/d）在0.12 ~ 0.68之间；最大近层速度变化在0.16 ~ 0.51 m/s之间，最大总剪应力（表层剪应力和弗劳德-克雷洛夫力之和）变化在0.386 ~ 2.06 Pa之间。总应力在确定海底沉积物和片流状态的稳定性方面是重要的。利用随自由流速度施加的卷积积分方法，结合一系列涡动黏度模型，对总剪应力和表皮剪应力进行了分析建模。波浪摩擦系数是利用波浪周期阶段的最大速度和瞬时速度，从波浪不同情况下的表皮剪应力（即最大正总剪应力时间、最大表皮剪应力时间和最大速度时间）估计出来的。同样，从总应力得到的力系数在最大正、负总应力和最大速度时估计。最大正总剪应力约为最小负总剪应力的1.5倍。使用最佳卷积模型，模拟和测量的床层正剪应力具有良好的相关性，但模型低估了数据约4%。摩擦因素取决于使用常规的最大速度或瞬时速度进行归一化的选择。它们之所以不同，是因为应力通常与速度不是同相的。摩擦系数与以往单色波的数据一致，并与雷诺数的平方根成反比。总剪应力使自由流流体速度增加约50°，而表面摩擦剪应力使自由流流体速度增加约30°，这与早期研究人员报道的结果相似。
Direct measurements of bed shear stresses (using a shear cell apparatus) generated by non-breaking solitary waves are presented. The measurements were carried out over a smooth bed in laminar and transitional flow regimes (~ 104< Re< ~ 105). Measurements were carried out where the wave height to water depth (h/d) ratio varied between 0.12 and 0.68; maximum near bed velocity varied between 0.16 m/s and 0.51 m/s and the maximum total shear stress (sum of skin shear stress and Froude–Krylov force) varied between 0.386 Pa and 2.06 Pa. The total stress is important in determining the stability of submarine sediment and in sheet flow regimes. Analytical modeling was carried out to predict total and skin shear stresses using convolution integration methods forced with the free stream velocity and incorporating a range of eddy viscosity models. Wave friction factors were estimated from skin shear stress at different instances over the wave (viz., time of maximum positive total shear stress, maximum skin shear stress and at the time of maximum velocity) using both the maximum velocity and the instantaneous velocity at that phase of the wave cycle. Similarly, force coefficients obtained from total stress were estimated at time of maximum positive and negative total stress and at maximum velocity. Maximum positive total shear stress was approximately 1.5 times larger than minimum negative total stress. Modeled and measured positive bed shear stresses are well correlated using the best convolution model, but the model underestimates the data by about 4%. Friction factors are dependent on the choice of normalizing using the maximum velocity, as is conventional, or the instantaneous velocity. These differ because the stress is not in phase with the velocity in general. Friction factors are consistent with previous data for monochromatic waves, and vary inversely with the square-root of the Reynolds number. The total shear stress leads the free stream fluid velocity by approximately 50°, whereas the skin friction shear stress leads by about 30°, which is similar to that reported by earlier researchers.
影响因子：
4.4
作者：
Barnes, M. P.;O'Donoghue, T.;Baldock, T. E.
通讯作者：
Baldock, T. E.