Local Similarity Between Aeolian Barchan Dunes and Their Downsized Subaqueous Counterparts

Aeolian barchan dunes on Earth and other planets have been widely investigated. Much of the understanding of barchan dune morphodynamics comes from field observations, numerical simulations, and downsized water-tunnel experiments as well. Many of the evolution of barchan dunes in water-tunnel experiments are similar to those of aeolian cases, although they have notable differences in scale, sand particle motion and hydrodynamic characteristics. Here, we first review the literature on the local similarities between aeolian and downsized subaqueous barchan dunes, focusing on (a) dune formation, (b) dune morphology, (c) particle-scale characteristics, and (d) sand/dune emission at horns. A comprehensive description of double-dune interaction modes is then presented to illustrate the local similarity of barchan dune morphodynamics. Specifically, as the interaction mode undergoes a process of “merging-splitting-chasing,” the similarity between the interaction modes of aeolian and downsized subaqueous dunes continuously decreases. Furthermore, we summarize the significance and limitations of downsized water-tunnel experiments for barchan dunes, and highlight the focus for future investigation.