Intensification of the Detached Flow in a Single Row of Inclined Oval Trench Dimples on the Wall of a Narrow Channel

An analysis of the intensification of a steady-state detached turbulent air flow with Re = 10 4 in a row of oval trench dimples, positioned on the wall of a narrow channel and oriented at an agile of 45 o to the incident flow, is given. It is shown that the anomalously high velocities of the reverse and secondary flows at the entrance of such a dimple (of the order of the mean mass velocity of the flow in the channel), as well as the negative friction in this part of the dimple that exceeds in absolute value the friction on the plane wall of the channel by almost five times, are due to the difference between the total pressure in the near zones of stagnation of the air flow at the windward slope of the dimple and the negative pressure at the site of generation of a whirlwind-like vortex structure in the dimple.