Метастабильные отрывные структуры при турбулентном обтекании круглых и овальных лунок

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.