Approximate uniformity of the size distribution in the crescent-shaped dune swarm: A downsized experimental reinvestigation

Crescent-shaped dunes, or barchans, usually move in swarms in nature, where their sizes become closer to each other while migrating downstream collectively. A major cause of such a phenomenon is the collision among the dunes. Therefore, it is of importance to elucidate the pattern of the local dune interaction process, i.e., the double-dune collision. In this study, based on a downsized water tunnel experiment that adopts two colors of sand samples, the double-dune collision pattern is parameterized, which is investigated as a function of the initial mass ratio of the two dunes. The results depict from a distinctive perspective that the double-dune collision is essential in realizing the uniformity of the size distribution in a dune swarm. The proposed concepts could aid in the development of a comprehensive parameterization for the double-dune collision system.