At present paper, mechanisms which determine turbulent separated flow structures inside oval-trench dimples are described. In cases of short trenches, includes the semi-spherical dimple, three regimes exist: symmetrical and two mono-core asymmetrical. It should be noted, asymmetrical regimes are metastable, while the symmetrical regime is unstable. Therefore, for short dimples, an actual flow pattern has an unsteady nature, which is characterized by switching between two mono-cores vortex structures. With an increase in the length of dimples, the symmetrical regime becomes a stable and an actual flow pattern has a quasi-steady character. Further increase of dimple's length produces more complex flow topology with persisting of the quasi-steady nature.

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.