Affiliation:
1. National Inland Waterway Regulation Engineering Research Center, Chongqing Jiaotong University, Chongqing 400074, China
Abstract
Rough-bed open-channel flows (OCFs) are ubiquitous in rivers and canals. However, the scaling and energy contents of very-large-scale motions (VLSMs) in such flows remain unclear. In this study, the above characteristics of VLSMs are experimentally investigated with the measurement of particle imaging velocimetry (PIV). VLSM wavelengths obtained via premultiplied spectra analysis were consistent with previously reported values. Comparisons with these studies ruled out the role of relative submergence, and suggested that the channel aspect ratio is key to controlling the VLSM wavelengths in OCFs. VLSMs carry approximately 60% of the turbulence kinetic energy (TKE) and 38–50% of the Reynolds stress in rough-bed OCFs. The VLSM-related TKE fraction in the 0.1–0.5H range increased with increasing friction Reynolds number, while variation in the Reynolds shear stress did not exhibit any explicit trend.
Funder
National Natural Science Foundation of China
the Three Gorges Follow-up Scientific Research Project of China
Subject
Water Science and Technology,Aquatic Science,Geography, Planning and Development,Biochemistry