Author(s): J. Adjetey; Subhadip Das; Ram Balachandar

Linked Author(s): Ram Balachandar

Keywords: Suspended cylinder; SPIV; RST; LES; Gap ratio

Abstract: In the present study, flow characteristics and turbulence distributions around a suspended smooth circular cylinder were investigated by a combination of experimental and computational methodology. The experimental measurements were carried out using stereo particle image velocimetry (SPIV), whereas computational models were developed by employing Reynolds Stress Transport (RST) and Large Eddy Simulation (LES). The cylinder was kept suspended in an open channel flow using a carefully designed mount and maintaining a variable gap (g) with the bottom wall of the laboratory flume. Wake flow pattern is monitored for two different gap sizes: g = 0.5d and 1.0d, where d is the diameter of the cylinder. The objective of the current study is to evaluate the performance of the computational models against the experimental data for a complicated flow field involving a boundary layer, a wake, and a jet-like flow between the body and the bed. For this purpose, the contours of mean velocities on the wake mid-vertical plane are compared between the experimental (SPIV) and computational (RST and LES) results. It is found that RST simulation overpredicts the length of the recirculation region both at the bottom of the cylinder and in the wake region. This deviation of RST data from the experimental dataset is more evident in the Reynolds stress distributions. Furthermore, the location of maximum stress also varies based on the computational model used. It illustrates the complexities of the flow around a suspended cylinder and emphasizes the necessity of advanced computational techniques like LES for precise analysis.

DOI: https://doi.org/10.3929/ethz-b-000675921

Year: 2024