Experimental Studies of Turbulence in the Surface Layer: Phase IV

9415003 Frenzen这项研究将评估在方程中的湍流动能（TKE）在表面层的粗糙度雷诺数的函数，以及通过进行和附加实验在萨斯喀彻温省中北部的一个广泛的森林稳定性的变化。 为进行BOREAS试验而临时在该处安装的一座26米高的塔提供了一个及时的机会，以确定在选定的“理想”实地进行的早期将军澳支线研究的天气结果也适用于更现实的地形。 最近在两个相对平坦的地点（zo 5厘米）进行的实验所提出的问题，将在粗糙得多的森林冠层（zo 50厘米）进行调查，使用经过验证的程序和早期工作的设备开发。 这些问题包括：a）湍流能量产生率和耗散率之差（耗散亏损）随粗糙度雷诺数的增加而变化多少？ B）高阶项、湍流项和压力输运项如何适应粗糙表面上能量平衡的这些变化？ 以及c）冯卡门常数是否随粗糙度雷诺数继续减小到理论极限0.37？ 所获得的结果将被用来开发广义条款适用于TKE方程的表面层流量超过真实的地形，并将被用来确定各种缩放假设的准确性提出的流量超过森林。

9415003 Frenzen This research will evaluate changes in the equation for turbulent kinetic energy (TKE) in the surface layer as a function of roughness Reynolds number as well as stability by conducting and add-on experiment over an extensive forest in north central Saskatchewan. A 26-m tower temporarily installed in this location for the BOREAS experiment offers a timely opportunity to determine weather findings of earlier TKE studies conducted over selected "ideal" field sites also apply over more realistic terrain. Questions raised by recent experiments over two relatively smooth sites (zo 5 cm) will be investigated over the much rougher forest canopy (zo 50 cm) using proven procedures and equipment development for the earlier work. These questions include: a) How much does the difference between rates of turbulent energy production and dissipation (the dissipation deficit) changes with increasing roughness Reynolds number? b) How do the higher-order, turbulence and pressure transport terms adjust to these changes in the energy balance over rough surfaces? and c) Does the von Karman constant continue to decrease with roughness Reynolds number to the theoretical limit of 0.37? Results obtained will be used to develop generalized terms for applying the TKE equation to surface layer flows over real terrain, and will be used to determine the accuracy of various scaling hypotheses proposed for flow over forests.