Abstract
Direct numerical simulations were carried out to study turbulent-laminar pattern in the Poiseuille flow at low Reynolds number. The turbulent-laminar pattern consists of turbulent and quasi-laminar regions that are alternatively arranged in the streamwise direction and form striped pattern. Streamwise vortical structures identified by the second invariant of the deformation tensor are detected and conditionally averaged. As a result, the number of the vortices in the downwind turbulent region was much smaller than that in upwind turbulent region when approaching the wall. Moreover, asymmetry in the numbers of clockwise and counterclockwise vortices occurred in the upwind and downwind turbulent regions. This is due to the existence of the mean spanwise flows in each region.
