Numerical modeling of interaction of turbulent flow with trash screen in open channels

Abstract

Trash screens are widely employed at the entrance of hydraulic structures, water intakes, and pumping stations to trap flowing debris that could exasperate downstream troubles. The characteristics of the vertical trash screen flow are measured using a Three-Dimensional Acoustic Doppler Velocimetry instrument for different flow conditions. The governing equations of the flow are numerically solved using k–ω SST, k–ϵ STD, k–ϵ RNG, and Reynolds Stress Model (RSM) and Large Eddy Simulations (LES). ANSYS-Fluent is used for these numerical simulations. The free surface of the vertical trash screen flow is computed by the volume of fluid method. The Grid Convergence Index is used to analyze the impact of the chosen grid structure on the numerical results. Experimental measurements of the velocity field and free surface profiles are compared with the numerical results of 3D simulations for validation. This study aims to identify the behavior of flow through screens in more detail through experimental and numerical simulations. The computed flow profiles considering all five cases agree well with the measured profile, whereas streamwise velocity in most portions of the flow, the k-ω SST outperforms the other models, and the RSM turbulence model is the second most effective.