Biferale L, Mantovani F, Sbragaglia M, Scagliarini A, Toschi F, Tripiccione R
Department of Physics and INFN, University of Tor Vergata, Rome, Italy.
Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Jul;84(1 Pt 2):016305. doi: 10.1103/PhysRevE.84.016305. Epub 2011 Jul 14.
The parametrization of small-scale turbulent fluctuations in convective systems and in the presence of strong stratification is a key issue for many applied problems in oceanography, atmospheric science, and planetology. In the presence of stratification, one needs to cope with bulk turbulent fluctuations and with inversion regions, where temperature, density, or both develop highly nonlinear mean profiles due to the interactions between the turbulent boundary layer and the unmixed-stable-flow above or below it. We present a second-order closure able to cope simultaneously with both bulk and boundary layer regions, and we test it against high-resolution state-of-the-art two-dimensional numerical simulations in a convective and stratified belt for values of the Rayleigh number up to Ra∼10(10). Data are taken from a Rayleigh-Taylor system confined by the existence of an adiabatic gradient.
对流系统中以及存在强分层情况下小尺度湍流涨落的参数化，是海洋学、大气科学和行星学中许多应用问题的关键所在。在存在分层的情况下，人们需要应对整体湍流涨落以及逆温区域，在这些区域，由于湍流边界层与其上方或下方未混合的稳定流之间的相互作用，温度、密度或两者都会形成高度非线性的平均剖面。我们提出了一种能够同时处理整体区域和边界层区域的二阶闭合模型，并在一个对流和分层带中针对高达Ra∼10(10)的瑞利数，通过高分辨率的二维数值模拟对其进行了测试。数据取自一个受绝热梯度限制的瑞利 - 泰勒系统。
