论文标题
理想化的湍流唤醒，稳定，不均匀的环境密度分层
Idealised Turbulent Wake With Steady, Non-Uniform Ambient Density Stratification
论文作者
论文摘要
地球物理环境中的密度分层可能是不均匀的，尤其是在热盐阶层和大气层过渡中。然而，非均匀分层通常会因高度的平均环境密度变化而近似。这种近似通常是在数值模拟中进行的，因为它大大简化了计算。在本文中，分析了使用$ 4096 \ times 2048 \ times 2048 $网格点的直接数值模拟来解决在非均匀分层的流体中理想化的湍流唤醒，以了解假设线性分层的后果。 For flows with the same average change in density with height, but varied local stratification $d\bar ρ(z)/dz$, flow dynamics are dependent on the ratio $ξ=δ_{\cal U}/δ_ρ$, where $δ_{\cal U}$ and $δ_ρ$ are characteristic velocity and density vertical scale heights of the mean flow.结果表明，即使平均分层相当强，稳定的分层流将显示出类似于$ξ> 2 $的非构型流动的特性。特别是，结果表明，当$ξ> 2 $时，混合会增强。
Density stratification in geophysical environments can be non-uniform, particularly in thermohaline staircases and atmospheric layer transitions. Non-uniform stratification, however, is often approximated by the average ambient density change with height. This approximation is frequently made in numerical simulations because it greatly simplifies the calculations. In this paper, direct numerical simulations using $4096 \times 2048 \times 2048$ grid points to resolve an idealised turbulent wake in a non-uniformly stratified fluid are analysed to understand the consequences of assuming linear stratification. For flows with the same average change in density with height, but varied local stratification $d\bar ρ(z)/dz$, flow dynamics are dependent on the ratio $ξ=δ_{\cal U}/δ_ρ$, where $δ_{\cal U}$ and $δ_ρ$ are characteristic velocity and density vertical scale heights of the mean flow. Results suggest that a stably stratified flow will demonstrate characteristics similar to nonstratified flow when $ξ> 2$, even though the average stratification is quite strong. In particular, the results show that mixing is enhanced when $ξ> 2$.
