EFFECT OF INERTIAL WAVES ON THE STABILITY OF THE LIQUID - GRANULAR MEDIUM INTERFACE IN A LIBRATING CYLINDER
The dynamics of a liquid and a granular medium in a horizontal cylinder rotating at a variable velocity (librating) is experimentally studied. In a rapidly rotating cylinder, the granular medium forms a thin cylindrical layer on the lateral surface of the cavity. Librations lead to the appearance of an oscillating motion in viscous boundary layers. The latest are sources of the inertial waves, which arise near the connection of the cylindrical and end walls. The reflection of the waves from the liquid - granular medium boundary leads to the generation of steady toroidal flow in the Stokes boundary layer. As a result, there is the formation of ring structures from small particles of coal at the interphase boundary. With an increase of the amplitude of librations in the initially axisymmetric surface of the granular medium, a regular relief in the form of dunes arises in a threshold manner. The effect of the inertial waves on the threshold of the occurrence of the relief is investigated in present paper.