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Volume 130 (2015)

CONTENTS

No. 130, 2015, 93–107

The decay power law in turbulence generated by grids
JOANNA GRZELAK, ZYGMUNT WIERCIŃSKI

Abstract

It is well known that turbulence in the flow can be characterized by two main parameters: the intensity and scale (such as macro- or microscale of length, time or speed). Turbulence in wind tunnels can be generated by a variety of means (placed perpendicularly to the flow) like passive and active grids, most often grids of round or square wires, perforated plates and so on. The aim of this study is to gain a detailed knowledge of the degree of turbulence isotropy and homogeneity in the flow behind the grids of variable geometry. For this purpose, skewness and kurtosis of the velocity fluctuations and also transverse variation for five grids of different parameters were determined. Additionally, some new results on the influence of the initial conditions of turbulence generation on the decay law of turbulence are given.

Keywords:

turbulence generation, turbulence intensity, grid, isotropy, homogeneity
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