Evolution of Energy in Submerged Granular Column Collapse
Wen-Tao Zhang1,2, Yi An2, Qing-Quan Liu3*, Xiao-Liang Wang3, and Yun-Hui Sun3
1School of Engineering Sciences, University of Chinese Academy of Sciences, Beijing 100049, China 2Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China, 3Department of Mechanics, Beijing Institute of Technology, Beijing 100081, China
Abstract：The evolution of energy in subaerial and subaqueous granular column collapses is studied. Employing the refractive index matching method and planar laser-induced fluorescence technique, we obtain granular and liquid images simultaneously in a single experiment of subaqueous flow. Particle image velocimetry and particle tracking velocimetry are used to process the data for the fluid and granular phase. We find stepwise decreases in the total kinetic energy of the granular material. The stage of rapidly falling energy corresponds to large transverse changes in the direction of the massive granular particles. Moreover, in this stage, a major fraction of the granular kinetic energy transferred from the granular potential energy is lost or transferred. Interestingly, compared with dry granular flow, the existence of an ambient liquid seems to reduce the total dissipated energy, which may be the reason why previous studies observed similar granular runout distances in subaqueous and dry granular collapses.
2020, Vol. 37 
