Author(s): Reza Azizi; Mehdi Ghomeshi
Linked Author(s):
Keywords: Vortex; Transverse wave; Strouhal Number; Open channels
Abstract: There are many instances where internal and external flows of fluids have to pass aside a set of rods on their path. If a cluster of circular cylinders place perpendicular in the flow path, the overlap of vortices, resulted from the stream lines separation around each rod leads in the vortex-induced vibration. The water flow through vegetation covered floodplain of rivers, around bridge piers and jetty piers are typical examples of liquid flow around circular cylinders. The majority of previous researches have investigated the vibration due to vortex in closed conduits containing gas fluids. Moreover the proposed graphs and equations for determining Strouhal Number are applicable for gas fluids. The present study has been conducted in a rectangular laboratory flume. During this study 22set of experiments, each with a different arrangement of circular cylinders were conducted. As the flow streams pass through the laboratory flume the vortex street take place and in specific hydraulic conditions of flow, 4 modes of surface waves are seen across the flume. These waves have a transverse and standing form which is supposed to be linear. The maximum wave amplitude observed during experiments was 43%of average flow depth. Also two equations are proposes for determination of Strouhal Number in open channels flow.
Year: 2010