Numerical simulation and analysis of horseshoe-shaped vortex in near-wall region of turbulent boundary layer

The low-Reynolds-number full developed turbulent flow in channels is simulated using large eddy simulation (LES) method with the preconditioned algorithm and the dynamic subgrid-scale model, with a given disturbance in inlet boundary, after a short development section. The inlet Reynolds number based on momentum thickness is 670. The computed results show good agreement with direct numerical simulation (DNS), which include root mean square fluctuated velocity distribution and average velocity distribution. It is also found that the staggered phenomenon of the coherent structures is caused by sub-harmonic. The results clearly show the formation and evolution of horseshoe vortex in the turbulent boundary layer, including horseshoe vortex structure with a pair of streamwise vortexes and one-side leg of horseshoe vortex. Based on the results, the development of the horseshoe-shaped coherent structures is analyzed in turbulent boundary layer.