The slope of the oval-trench dimple in the corridor package on the hydrodynamic stabilized section of the narrow channel has a dramatic effect on the anomalous intensification of returned and swirling flows in the dimple, leading to a 3–4-fold decrease in relative negative friction in the range of angles from 40° to 60°, an increase in the highest speed return and secondary flows up to 0.8 and 1.18 with respect to the mass-average flow velocity in the channel.

A numerical study of the effect of blowing a jet from a thin air tube on the vortex motion in an inclined groove on the wall of a plane-parallel channel is performed using StarCCM+ calculation codes. It is shown that in the range of change in the flow rate in the jet from 0 to 0.1% in fractions of the air flow rate in the channel, the blowing of the jet does not affect the self-organized tornado-like vortex in the inlet part of the groove. With an increase in the relative flow rate, the outflowing trickle is gradually drawn in, and, starting from 0.08%, it is completely captured by a helical vortex emerging from the central part of the groove with an inclination angle of 45°. In this case, the swirling flow in the tail part of the groove is intensified due to the resulting pressure drop between the zones of stagnation on the windward slope and rarefaction at the bottom of the groove.

Based on the solution of the URANS closed with a modified model of turbulence MSST, the separated flow in a narrow channel with a conical dimple on the wall with a coning angle of θ was calculated. It is noted that there is a sharp transition from the periodic mode with two alternately changing vortices in close to cylindrical (θ = 10о-22.5о) dimples to modes with periodic low-frequency oscillations of inclined mono-tornado structures at moderate θ (30о-37.5о) and with steady vortex structures at θ above 45о. Relative hydraulic losses in the irradiated section of the channel with an increase in θ remain at the level of 1.23-1.24 to θ = 45о, and then quickly decrease by almost 1.5 times to 1.16 at θ = 60о.