| 摘要: |
| 内孤立波破碎混合是陆架地形上海洋混合过程重要的能量汇,为了探究内孤立波在连续跃层密度分层中能量变化及能量耗散规律,本文使用OpenFOAM建立数值水槽,基于双曲正切曲线设置连续跃层密度分层开展了一系列工况的模拟,针对跃层厚度对内孤立波能量传递及其耗散进行了详细分析。结果表明跃层厚度与跃层处流速剪切存在着负相关关系,随着跃层厚度的增加能量耗散先减小后增大。跃层厚度较小时,跃层处流速剪切强,理查德森数小,易产生开尔文-亥姆霍兹(Kelvin–Helmholtz)不稳定现象;随着跃层厚度的增大,流速剪切减小,理查德森数增大,开尔文-亥姆霍兹不稳定消失;跃层厚度达到临界值后,层结稳定性减小,理查德森数减小,流场的翻转混合过程加强,能量耗散也明显增强。 |
| 关键词: 内孤立波 OpenFOAM 跃层厚度 能量耗散 |
| DOI：10.11759/hykx20230215001 |
| 分类号:P731.24 |
| 基金项目:国家自然科学基金项目(41876015, 62161045) |
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| Effect of pycnocline thickness on energy dissipation of internal solitary waves |
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ZHANG Qunxing1, XU Yu2, LIU Juan3, MENG Jing1, WANG Guixia4, CHEN Xu1
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1.College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China;2.College of Engineering Ocean University of China, Qingdao 266100, China;3.Beijing Institute of Applied Meteorology, Beijing 100029, China;4.College of Mathematics Science, Inner Mongolia Normal University, Hohhot 010022, China
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| Abstract: |
| The dynamics and energy transference involved in the breaking of internal solitary waves are crucial in the process of ocean mixing on the continental shelf. To understand the energy shifts and dissipation patterns of these waves within the continuous pycnocline density stratification, this research involves using OpenFOAM to establish a numerical flume and performing several simulations based on a hyperbolic tangent curve designed to establish the stratification. Moreover, the research involves analyzing the energy transfer and dissipation of internal solitary waves relative to the pycnocline thickness in detail. Results show that the pycnocline thickness has an important impact on the redistribution and energy dissipation of the internal solitary wave energy. A thinner pycnocline results in stronger stratification, leading to increased flow velocity shear at the pycnocline and a reduced Richardson number. This scenario is prone to generate Kelvin–Helmholtz (KH) instability. Conversely, a thicker thermocline can inhibit KH instability, causing an initial increase in the Richardson number. However, as the thermocline thickness is further increased, the change in velocity shear becomes larger than the stratification change. Consequently, the Richardson number decreases, strengthening the mixing and overturning process of the flow field and significantly enhancing energy dissipation. This work is of great significance with regard to the improvement of ocean internal wave mixing parameterization. |
| Key words: internal solitary wave pycnocline thickness OpenFOAM energy dissipation |
