大涡PIV方法测量水平矩形槽道内湍流耗散率

湍能耗散率的准确测量对工程实际和湍流的理论研究都有着重要的意义。以往的研究多是基于单点速度测量来估算单点的湍能耗散率或者有限体积内的平均值，而不能提供整个流场范围内的耗散率的分布情况。PIV能够测量瞬时流场的速度分布情况，它更适合于用来测量整个流场内的耗散率分布。本文分析了PIV测量得到的速度与单点测量方法之间的关系，提出了大涡PIV方法，运用大涡模拟中的亚网格尺度(SCS)应力模型，对PIV测量结果进行处理得到了水平槽道内的耗散率的分布。对采用不同SCS模型的结果以及量纲分析的结果进行了比较。

Estimation the turbulent dissipation rate in a horizontal rectangular duct by large eddy PIV method

Accurate estimation of turbulent dissipation rate is very important to the engineering and turbulent theory. Previous studies, which are limited to single-point velocity measurement techniques ,mainly focus on measuring the single-point local dissipation rate or average rate over a finite volume, cannot provide the distribution of the dissipation rate for the whole field. Since the particle image velocimetry(PIV) is capable of providing multi-point instantaneous measurements of a velocity field, it is more suitable for estimating the dissipation rate. In this paper , the relationship between the velocities captured by PIV and single-point measurement method is analysed, and a large eddy PIV method is proposed. Based on this method, the measurement results of horizontal duct flow by PIV are applied for estimating the turbulent dissipation rate by using different sub-grid scales (SGS) stress models. The results obtained by large-eddy PIV method and dimensional analysis are compared and analysed as well.