Stratification effects on shoaling internal solitary waves
Stratification effects on shoaling internal solitary waves
复制标题
DOI：
10.1017/jfm.2021.1049
复制
发表时间：
2021-03
影响因子：
3.7
通讯作者：
S. G. Hartharn-Evans;M. Carr;M. Stastna;P. Davies
中科院分区：
文献类型：
--
作者：
S. G. Hartharn-Evans;M. Carr;M. Stastna;P. Davies
摘要本文结合数值模拟和实验室研究，探讨了层结形式对光滑线性地形斜坡上传播的内孤立波的浅水特性的影响。三种分层类型进行了研究，即（一）薄tanh（均匀的上层和下层由薄密度跃层分离），（二）表面分层（线性分层层覆盖均匀的下层）和（iii）广泛tanh（连续的密度梯度整个水柱）。结果表明，层结的形式影响着浅水波的破碎类型。在薄的tanh分层，良好的协议被视为与过去的研究。波浪在最浅的斜坡上发生分裂。对于给定的地形坡度，随着波陡A_w/L_w$的增加，破碎类型从涌浪到崩塌再到倾伏，其中A_w$和L_w$分别为入射波的振幅和波长。在表面分层制度，打破分类不同于薄tanh分层。整个上层的密度梯度抑制了倾伏动力学，而在参数空间中的等效位置，在薄的tanh分层中形成了反折型破碎带。在广泛的双曲正切剖面制度，暴跌动力学同样受到抑制，近底密度梯度防止崩溃的动力学。相反，所有的波浪要么分裂，要么形成汹涌的碎浪。由于波陡度在广泛的双曲正切分层的增加，由浪涌形成的弹丸表现出开尔文-亥姆霍兹不稳定性的证据，其上边界。在两个二维和三维模拟，波涛大小的增长与波陡度的增加，动力学以前没有观察到的文献。
Abstract This combined numerical/laboratory study investigates the effect of stratification form on the shoaling characteristics of internal solitary waves propagating over a smooth, linear topographic slope. Three stratification types are investigated, namely (i) thin tanh (homogeneous upper and lower layers separated by a thin pycnocline), (ii) surface stratification (linearly stratified layer overlaying a homogeneous lower layer) and (iii) broad tanh (continuous density gradient throughout the water column). It is found that the form of stratification affects the breaking type associated with the shoaling wave. In the thin tanh stratification, good agreement is seen with past studies. Waves over the shallowest slopes undergo fission. Over steeper slopes, the breaking type changes from surging, through collapsing to plunging with increasing wave steepness $A_w/L_w$ for a given topographic slope, where $A_w$ and $L_w$ are incident wave amplitude and wavelength, respectively. In the surface stratification regime, the breaking classification differs from the thin tanh stratification. Plunging dynamics is inhibited by the density gradient throughout the upper layer, instead collapsing-type breakers form for the equivalent location in parameter space in the thin tanh stratification. In the broad tanh profile regime, plunging dynamics is likewise inhibited and the near-bottom density gradient prevents the collapsing dynamics. Instead, all waves either fission or form surging breakers. As wave steepness in the broad tanh stratification increases, the bolus formed by surging exhibits evidence of Kelvin–Helmholtz instabilities on its upper boundary. In both two- and three-dimensional simulations, billow size grows with increasing wave steepness, dynamics not previously observed in the literature.