...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of the Atmospheric Sciences >Variability of turbulence and its outer scales in a model tropopause jet
【24h】

Variability of turbulence and its outer scales in a model tropopause jet

机译：模型对流层顶射流中湍流及其外部尺度的变化

获取原文
获取原文并翻译 | 示例
   

获取外文期刊封面封底 >>

       
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Variability of flow regimes and turbulence scalings in a model of an inhomogeneously stratified, tropopause jet is investigated through high-resolution, forced, three-dimensional numerical simulations (with 512 or 1024 vertical levels). Multivalued scaling branches, with respect to the local gradient Richardson number (Ri(g)), are shown to occur in several turbulent quantities (such as variances, fluxes, mixing efficiency, outer scales, and their ratios, etc.). Two distinct scaling curves are found for the upper and lower flanks of the jet, each showing a clear branch switching at a critical height. Distinct scaling curves in the upper and lower flanks of the jet can be related to the doubling of buoyancy frequency (N) in the background profile (across the model tropopause). The vertical levels corresponding to the inflection points (maximal shearing) in the quasi-equilibrium turbulent mean jet velocity profile is identified as the best criterion for branch switching along each of the scaling curves. A conceptual picture of regime transitions, for the jet-induced inhomogeneously stratified turbulence near the tropopause, is identified based on crossovers in various turbulence outer scales. Traversing away from the center of the jet, the following sequence of regime transitions may be identified: shear dominated --> buoyancy affected --> buoyancy dominated. In the innermost core, turbulence, relatively unaffected by shear and stratification, is maintained through a balance between transport and dissipation terms. It is also found that several of the turbulence scaling relations undergo a significant change at the transition from the buoyancy-affected to the buoyancy-dominated regime. Another significant feature is the extension of the outer scaling curve in the buoyancy-affected regime into the shear-dominated regime up to the inflection point level. This indicates that a portion of the latter regime is also influenced by stratification. Important scaling relations are deduced from the simulation results, and are compared with existing observationalumerical studies. [References: 73]
机译：通过高分辨率的强制三维数值模拟（垂直或垂直水平为512或1024），研究了不均匀分层的对流层顶射流模型中的流动形式和湍流尺度的变化。关于局部梯度理查森数（Ri（g））的多值缩放分支显示为以几个湍流量（例如方差，通量，混合效率，外部比例及其比率等）出现。对于射流的上部和下部侧面，发现了两条不同的缩放曲线，每条曲线都显示了在临界高度处清晰的分支切换。射流的上部和下部侧面的明显比例曲线可能与背景剖面（整个对流层顶）中浮力频率（N）的加倍有关。准平衡湍流平均射流速度曲线中与拐点（最大剪切）相对应的垂直高度被确定为沿着每个缩放曲线进行分支切换的最佳标准。基于对流湍流外部尺度的交叉，确定了对流层顶附近射流引起的非均匀分层湍流的状态转变的概念图。从喷气机的中心移开，可以识别出以下一系列政权过渡：剪切力主导->受浮力影响->浮力主导。在最内层的核中，湍流通过运输和耗散条件之间的平衡得以保持，而湍流相对不受剪切和分层的影响。还发现在从受浮力影响到以浮力为主的体系的过渡中，几种湍流比例关系发生了显着变化。另一个重要特征是在受浮力影响的区域中，外部比例缩放曲线一直延伸到以剪切力为主的区域，直至拐点水平。这表明后一种政权的一部分也受到分层的影响。从仿真结果中得出重要的比例关系，并将其与现有的观测/数值研究进行比较。 [参考：73]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号