Author(s): Patricia Xavier; Catherine Wilson
Linked Author(s):
Keywords: Open channel hydraulics; Obstructions; Vegetation; Double-averaging
Abstract: The double-averaging methodology (DAM) is applied here to characterise the streamwise velocity, turbulence intensity and form-induced stress intensity distribution in the flow around a staggered array of rigid cylinders under uniform flow conditions. The study is centred on the use of different sampling patterns, towards an attempt to identify an optimum sampling regime to capture representative values of key flow characteristics. Initially, a measurement grid of 69 vertical profiles within the experimental control volume was taken using a 25Hz Acoustic Doppler Velocimeter. This produced the high resolution grid of values of the flow and turbulence characteristics which provided the definitive values for comparison. Four sampling patterns were then adopted, selected from similar experiments in the literature, comprising of either two, six, seven or fourteen sampling verticals. It was found that the accuracy in the streamwise velocity improved proportionally with the number of sampling profiles, however this was not the case for turbulence intensity or form induced stress intensity, where the accuracy was poorer and more variable.
Year: 2007