Numerical simulations of turbulent spots in plane Poiseuille and boundary-layer flow

Abstract
Direct numerical simulations of turbulent spots in plane Poiseuille and boundary‐layer flows are performed. Mature, self‐similar spots are obtained. The propagation velocities and spreading angles are found to compare well with corresponding experiments. The difference in shape of the two spots is also clearly discernible: the turbulent parts are contained within arrowhead regions that point in opposite directions for the two cases. The wing‐tip region of the Poiseuille spot is also found to consist of a large‐amplitude semiturbulent wave packet.