NUMERICAL MODELING OF SECONDARY CURRENT CELLS IN TRAPEZOIDAL CHANNELS WITH UNIFORM ROUGHNESS

Trapezoidal open channels are among the most common and optimized sections that used in water conveyance system. Thus investigation of flow conditions in them is very essential. One of the most important related subjects is lateral velocity component that produced cells in secondary flow. Several parameters such as channel roughness can intervene on how cells were formed. In the present study applying CFD methods using ANSYS CFX package flow condition in trapezoidal open channels with roughed boundary were simulated and variation of cells in secondary flow and distribution of hydraulic parameters such as mean depth velocity and boundary shear stress under uniform increase of boundary roughness were investigated. The results showed changes in sizes as well as the cells location due to uniform roughness increase. Also this increase was caused decrease in mean depth velocity and increase in boundary shear stress.