The influence of the angle of inclination of single-row oval-trench dimples in the stabilized hydrodynamic section of a narrow channel on the anomalous intensification of the separated turbulent flow

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$^{\circ}$ to 60$^{\circ}$, 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.