基于大涡模拟的三角形地形之层结流体湍动能收支模型

为了探究海底地形对湍流动能收支的影响,本文使用并行大涡模拟模式(The Parallelized Large-Eddy Simulation Model,PALM),以坡陡作为无量纲地形参数(δ),设置了亚临界、临界和超临界三种地形状态(δ=0.5,1和2)进行数值模拟。文章计算并呈现了地形作用下的流体速度和湍流动能收支分布,以及湍流动能平衡方程各参量。通过回归分析和量纲分析重点讨论了地形顶点处耗散和海表处能量的耗散,与地形坡陡的关系,得出其关系均呈指数形式。     

Large-eddy simulation of the influence of a wavy lower boundary on the turbulence kinetic energy budget redistribution

Oceanic turbulence plays an important role in coastal flow. However, as the effect of an uneven lower boundary on the adjacent turbulence is still not well understood, we explore the mechanics of nearshore turbulence with a turbulence-resolving numerical model known as a large-eddy-simulation model for an idealized scenario in a coastal region for which the lower boundary is a solid sinusoidal wave. The numerical simulation demonstrates how the mechanical energy of the current is transferred into local turbulence mixing, and shows the changes in turbulent intensity over the continuous phase change of the lower topography. The strongest turbulent kinetic energy is concentrated above the trough of the wavy surface. The turbulence mixing is mainly generated by the shear forces; the magnitude of shear production has a local maximum over the crest of the seabed topography, and there is an asymmetry in the shear production between the leeward and windward slopes. The numerical results are consistent with results from laboratory experiments. Our analysis provides an important insight into the mechanism of turbulent kinetic energy production and development.