A Comparative Study between Sand- and Gravel-Bed Open Channel Flows in the Wake Region of a Bed-Mounted Horizontal Cylinder

Fluids

Kalpana Devi¹  Prashanth Reddy Hanmaiahgari¹  Ram Balachandar²  Jaan H. Pu³ 

[1] Department of Civil Engineering, IIT Kharagpur, Kharagpur 721302, India;Department of Civil and Environmental Engineering, University of Windsor, Windsor, ON N9B 3P4, Canada;School of Engineering, Faculty of Engineering and Informatics, University of Bradford, Bradford BD71DP, UK;

关键词: ADV;    bed-mounted horizontal cylinder;    gravel-bed;    sand-bed;    turbulence;    wake region;   

DOI  :  10.3390/fluids6070239

来源: DOAJ

【 摘 要 】

In nature, environmental and geophysical flows frequently encounter submerged cylindrical bodies on a rough bed. The flows around the cylindrical bodies on the rough bed are very complicated as the flow field in these cases will be a function of bed roughness apart from the diameter of the cylinder and the flow velocity. In addition, the sand-bed roughness has different effects on the flow compared to the gravel-bed roughness due to differences in the roughness heights. Therefore, the main objective of this article is to compare the mean velocities and turbulent flow properties in the wake region of a horizontal bed-mounted cylinder over the sand-bed with that over the gravel-bed. Three experimental runs, two for the sand-bed and one for the gravel-bed with similar physical and hydraulic conditions, were recorded to fulfil this purpose. The Acoustic Doppler Velocimetry (ADV) probe was used for measuring the three-dimensional (3D) instantaneous velocity data. This comparative study shows that the magnitude of mean streamwise flow velocity, streamwise Reynolds normal stress, and Reynolds shear stress are reduced on the gravel-bed compared to the sand-bed. Conversely, the vertical velocities and vertical Reynolds normal stress are higher on the gravel-bed than the sand-bed.

【 授权许可】

Unknown