Author(s): K. Basnet; R. Ettema
Linked Author(s):
Keywords: Unsteady flow; LSPIV; Velocity vector field; Wake-vortices; Vortex-shedding
Abstract: It is often necessary to determine the flow field and its velocity vectors associated with flow around hydraulic structures, such as bridge piers and abutments. Large-scale particle image velocimetry (LSPIV) holds potential promise for use as a means to obtain this information. However, there are no prior studies focused on the use of LSPIV to delineate unsteady flow fields dominated by large-scale turbulence structures as occur in the wake region immediately downstream of a structure. The present study comprised laboratory flume experiments using the LSPIV to assess how LSPIV can be applied for resolving unsteady flow features in the wake region behind a vertical cylinder in an open-channel flow. The use of optimized parameters, obtained by slight adjustment on estimated parameters, enabled the LSPIV method to produce expected velocity vector fields, including the vortex shed into the wake of a cylinder. The LSPIV-derived wake vortices and their frequency of shedding agreed with the estimated values obtained from the Strouhal number. It is concluded that, with optimal adjustment of parameters used for LSPIV technique, that the technique can be used successfully to estimate the actual shedding frequencies.
Year: 2011