Flow Analysis in Rigid Vegetation Using ANSYS

Abstract

Vegetation in bank of a river or stream has a major influence on resistance, velocity distribution and turbulence force.The resistance to flow in open channels depends on different channel and flow parameters.Out of many factors,vegetation is the mainly important parameter in open channels.Rigid vegetation in an straight channel change the flow of water due to the reason of energy loss during turbulence and by exerting additional drag forces on the moving liquid. Existence of vegetation in an open channel flow modify the velocity profile and the resistance in conditions of roughness coefficients.The velocity profile and the roughness coefficients of such channels change with the flow depths and section to section. One type of vegetation is used in this study, namely rigid vegetation using iron rods. The impact of the type of vegetation on velocity distribution of flow in an open channel (laboratory flume) was examined. The laboratory flume is rectangular in cross section and has dimensions of 12m length,0.60m width and 0.45m depth.An ADV flow meter was used to measure the flow velocity in each section of the channel. ANSYS software was used to measure the velocity distribution from experimental data. The results expose that inside the cylindrical rods’ layer, the velocity profile no longer follows the velocity of the flow of liquid logarithmic law profile reduces within vegetated region of the channel. It is identified that the added external drag force applied by plants reduces the mean flow velocity surrounded by vegetated section of the channel comparative to unvegetated section.