Measurement and prediction of bottom boundary layer hydrodynamics under modulated oscillatory flows
Measurement and prediction of bottom boundary layer hydrodynamics under modulated oscillatory flows
复制标题
调制振荡流下底部边界层流体动力学的测量和预测
DOI：
10.1016/j.coastaleng.2021.103954
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发表时间：
2021
影响因子：
4.4
通讯作者：
O'Donoghue T
中科院分区：
文献类型：
--
作者：
O'Donoghue T
在10个振荡流风洞实验中，使用LDA测量了砾石粗糙床和砂粗糙床上的底部边界层内的速度，这些实验涉及常规和调幅振荡流。相应的规则和调制流等效的均方根速度，振荡流周期，偏斜和不对称。将实验结果与基于具有k− ε湍流闭合的1DV RANS模型的预测结果进行了比较。分析了调制对单个流动半周期的流体动力学和对时间平均流体动力学的影响。湍流从一个半周期延续到下一个半周期，但半周期内的主要流体动力学特性（边界层厚度、峰值湍流动能、峰值湍流应力）对先前半周期流动条件的依赖性很小或没有依赖性。湍流传播的倾斜度，不对称性，时间平均的湍流动能和时间平均的湍流应力的床和垂直廓线显示调制的效果非常小。调制不影响由非对称流产生的时间平均速度剖面的形状，但它确实减小了幅度。RANS模型一般表现出良好的协议与测得的流体动力学以上约一粒直径的床，但由于其假设粗糙湍流，预测差的低速半周期的调制流的流体动力学的砂粗糙床。
Velocities are measured using LDA within the bottom boundary layer for 10 oscillatory flow tunnel experiments involving regular and amplitude modulated oscillatory flows over a gravel-rough bed and a sand-rough bed. Corresponding regular and modulated flows were equivalent in terms of rms velocity, oscillatory flow period, skewness and asymmetry. The experimental results are compared with predictions based on a 1DV RANS model with k− ϵ turbulence closure. The effects of modulation on the hydrodynamics of individual flow half-cycles and on the time-averaged hydrodynamics are analysed. Turbulence is carried over from one half-cycle to the following half-cycle but the main hydrodynamic properties within a half-cycle (boundary layer thickness, peak turbulent kinetic energy, peak turbulent stress) show little or no dependence on prior half-cycle flow conditions. Turbulence propagation from the bed and vertical profiles of skewness, asymmetry, time-averaged turbulent kinetic energy and time-averaged turbulent stress show remarkably little effect of modulation. Modulation does not affect the shape of the time-averaged velocity profile generated by the non-symmetric flows, but it does reduce the magnitude. The RANS model shows generally good agreement with the measured hydrodynamics above about one grain diameter from the bed, but, because of its assumption of rough turbulent flow, poorly predicts the hydrodynamics of the low-velocity half-cycles of the modulated flows over the sand-rough bed.
具有偏斜和不对称的波浪下的自由流速度描述
影响因子：
4.4
作者：
J. Malarkey;A. Davies
通讯作者：
A. Davies
影响因子：
2.3
作者：
A. Davies
通讯作者：
A. Davies
影响因子：
3.7
作者：
Van Der A D
通讯作者：
Van Der A D