Effect of Turbulent Model on the Accuracy of Numerical Simulation of Incompressible Flow over Backward Facing Step

Abstract

This study investigates effect of turbulence models and boundary layer simulation methods on the accuracy and run time of numerical simulation of the recirculation zone after the backward facing step. Expansion ratio and aspect ratio of the backward-facing step are 2.02 and 8, respectively. The numerical simulations are conducted in 6847 and 4926 Reynolds number (based on the hydraulic diameter of inlet channel and average inlet velocity). The Shear Stress Transport (SST) and the standard turbulence models are utilized and two cases of unstructured mesh are considered:1) near-wall coarse mesh and 2) near-wall fine mesh.The results show that the SST turbulence model predicts the reattachment length more accurately than the model along with enhanced wall treatment. Although, the standard model is less accurate, it's required CPU time is significantly shorter than the SST model.This study investigates effect of turbulence models and boundary layer simulation methods on the accuracy and run time of numerical simulation of the recirculation zone after the backward facing step. Expansion ratio and aspect ratio of the backward-facing step are 2.02 and 8, respectively. The numerical simulations are conducted in 6847 and 4926 Reynolds number (based on the hydraulic diameter of inlet channel and average inlet velocity). The Shear Stress Transport (SST) and the standard turbulence models are utilized and two cases of unstructured mesh are considered:1) near-wall coarse mesh and 2) near-wall fine mesh.The results show that the SST turbulence model predicts the reattachment length more accurately than the model along with enhanced wall treatment. Although, the standard model is less accurate, it's required CPU time is significantly shorter than the SST model.