Capture of gravel by the head of a dam-break wave in a dry bed

Abstract

It is experimentally found that a horizontal vortex is formed in the head of a dam-break wave, whose diameter is of the same order of magnitude as the wave amplitude. A close packing of vortex dipoles with a diameter of about the bottom particle size arises near the bottom. The central part of the dipoles lifts with the captured gravel and is twisted with the large vortex to form a wisp. The central part of the wisp lifts to form a wall composed of water and gravel.