Author(s): Ahmad Jafari; Mehdi Ghomeshi; Mahmood Bina; Seyed Mahmood Kashefipour
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Keywords: Transverse wave; Vortex shedding; Wave amplitude; Open channels
Abstract: There are many conditions in open channel flows where the steady flow of water passes a cluster of rigid vertical cylinders. These rigid cylinders may represent piers of bridge, jetty, or vegetation on the floodplain of rivers. In the paper attention is focused on the transverse waves generated in an open channel where the flow passes through a cluster of rigid vertical cylinders. The wooden circular cylinders with variation sizes were screwed into the bed of the flume at different distances and spacing. The waves were produced from the periodic forces created by the vortex shedding from the cylinders. In specific conditions these forces may create transverse waves with maximum amplitude in the channel. In this study, the height of the outlet control weir was changed from the highest to the lowest levels, with ten modes of oscillation occurring across the laboratory flume for each sequence. The discharge of flow was varied from 2.2 l/s to 25 l/s. The results provided an explanation for different wave formations that might occur due to vortex shedding when the flowing fluid is water was experimentally investigated. A new formulation was obtained from dimensional analyses, to estimate the amplitude of the transverse wave generated by vortex shedding in open channels.
Year: 2010