Free surface flow over square bars at different Reynolds numbers

Large-eddy simulations of free surface flow over bed-mounted square bars are performed for laminar, transitional and turbulent flows at constant Froude number. Two different bar spacings selected corresponding to k-type (reattaching flow) roughness, respectively. The validated with experimental data convincing agreement between simulation measurement is obtained in terms water elevations streamwise velocity profiles. deforms response the underlying bed roughness ranging from mild undulation distinct standing waves roughness. instantaneous deformations increase an Reynolds Contours mean wall-normal velocities, total shear stress streamfunction reveal presence extension recirculation zones trough two consecutive bars. governed by strong local gradients as a result rough deformed surface. number increases low decreases exhibit very similar distribution pressure coefficient Cp both cases, whilst generally lower laminar flow. Regarding friction coefficient, Cf, it significantly case than cases. spacing does not affect relative contribution forces force, neither factor greater increasing