Turbulence over cube-mounted rough bed using spatiotemporal averaging approach

Abstract

The paper describes an experimental study carried out in a laboratory flume to investigate the turbulent characteristics of cube mounted rough bed (3D flow). The three-dimensional (3D) velocity data are analyzed within the framework of double time-space averaging approach. The study particularly focuses on the changes induced in the mean velocities, turbulent intensities, Reynolds shear stresses, and form-induced normal and shear stress profiles both in time and space domains. The mean velocity profile shows two distinct distributions: linear distribution below the roughness crest and logarithmic distribution above the roughness crest. Within the roughness layer near the bottom, the form-induced stress changes significantly with roughness spacing. To highlight the stress terms and associated turbulent events, the quadrant analysis is performed using form-induced velocity fluctuations. Further, the turbulent kinetic energy budget is also analyzed to examine the bursting events comprehensively.