Uncertainty of propagation and entrainment characteristics of lock-exchange gravity current
Uncertainty of propagation and entrainment characteristics of lock-exchange gravity current
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DOI：
10.1007/s10652-022-09904-y
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发表时间：
2022-12
影响因子：
2.2
通讯作者：
Yeping Yuan;Dongrui Han;Zhiguo He;Jie Xiong;Jiaxin Zhang;Ying-Pin Lin
中科院分区：
文献类型：
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作者：
Yeping Yuan;Dongrui Han;Zhiguo He;Jie Xiong;Jiaxin Zhang;Ying-Pin Lin
在这项研究中，在良好控制的条件下进行了重复的锁交换实验，以评估宏观传播和夹带过程的不确定性和当前参数的统计变化/相关性。结果表明，在重力流传播过程中，波瓣和裂隙结构的振幅增大，波长变短，增大了重力流传播的不确定性。较大的密度差抑制了波瓣和裂隙结构的分裂过程，减小了电流前沿的波动程度。经Shapiro-Wilk检验，重力流宏观传播参数均符合正态分布。无因次海流锋速与锋高的映射关系呈“圆形”模式，而无因次海流锋速与锋高的对应关系呈“楔形”模式。混合层面积变异系数的演变趋势是两个准平稳周期之间由一个急剧下降连接。前一个准平稳周期的变异性强于后一个准平稳周期，且两个准平稳周期的变异强度均与初始密度差呈正相关。由于混合层的演化，卷吸过程早期的不确定性占主导地位。然而，叶瓣和裂缝结构提供了另一个不确定性来源的卷吸系数在后期阶段。此外，图像分辨率带来的电流传播的不确定性远远小于重力流本身演化形成的不确定性。
In this study, repeated lock-exchange experiments under well-controlled conditions were carried out to evaluate the uncertainty of the macro-propagation and entrainment process and the statistical variation/correlation of the current parameters. The results show that the lobe and cleft structures grow in amplitude while short in wavelength as current propagates, which enlarges the uncertainty of the gravity current propagation. A larger density difference inhibits the split process of the lobe and cleft structures and reduces the fluctuation degree of the current front edge. The macroscopic propagation parameters of the gravity current for the repeated experiment all meet the normal distribution, confirmed by the Shapiro–Wilk test. The mapping relationship between the dimensionless current front velocity and the front height forms a “circle-shaped” mode, while the corresponding relationship between the dimensionless current front velocity and the front height performs wedge-shaped. The evolution trend of the variation coefficient of the mixing layer area is that the two quasi-stationary periods are connected by a sharp decline. The variability of the former quasi-stationary period is stronger than the latter one, and the variation strength of the two quasi-stationary periods is both positively correlated with the initial density difference. The uncertainty at the early stage of the entrainment process is dominated due to the evolution of the mixing layer. However, the lobe and cleft structure provide another uncertainty source of the entrainment coefficient at the later stage. In addition, the uncertainty of the current propagation brought by image resolution is far less than that formed by the evolution of the gravity current itself.