Turbulent Flow Around Obstacles: Simulation and Study with Variable Roughness

Abstract

The present work aims to investigate the recirculation and incipient mixing zones in a channel flow supplied with obstacles. The main objective is to develop a new technique to control these recirculation zones by setting a variable roughness. For the purpose of varying that roughness, 4 small bars of heights 0.25H, 0.5H, 0.75H and H were placed downstream of the obstacle; H is the height of the obstacle. For this, a three-dimensional numerical approach was carried out using the ANSYS CFX computer code. In addition, the governing equations were solved using the finite volume method. The K-ω shear-stress transport (SST) turbulence model was utilized to model the turbulent stresses. In the end, we presented the time-averaged simulation results of the contours of the current lines (3D time-averaged streamlines, trace-lines), three components of the velocities: <u> (velocity u contour), <v> (velocity v contour) and <w> (velocity w contour), trace-lines, stream ribbons and mean Q-criterion iso-surface.

Experimental and Numerical Study of Open Channel Flow with T-Section Artificial Bed Roughness

“…Recently, several studies that investigated an artificial bed roughness have been carried out on increasing the manning coefficient in the open channel flow. Most studies in this field have investigated the effect of these roughs on the whole bed surface such as Noori and Saeed [4], Graf and Blanckaert [5], Hendratta et al [6], Ibrahim and Noori [7], Pradhan et al [8], Khoudja and Soudani [9], Yousfi and Aliane [10], and Majeed and Ghazal [3], who conducted a series of CFD simulations with the k-ω SST model were used to calculate Manning's coefficient of artificial geometric roughness element. These elements were placed on the flume's bed and were subjected to various transverse spaces and different angles of attack.…”