Investigation of the stabilities of barchan dune evolution under collision by a downscaled water tunnel experiment
A field of size-selected barchan dunes are found in widely diverse environments to migrate stably for sufficiently long time and distance, in which the binary-collision accounts for the internal stability. To explore whether the laws of the characteristic times in the solitary dune evolution can be maintained in the binary-collision system, a water tunnel experiment was carried out, in which three features of stability for the binary-collision system has been concluded. The first and the second feature indicate that the binary-collision system is approximately non-divergent and non-dissipative, respectively. The third feature indicates that the turnover time of a targeted dune is irrelevant with the upstream dune, while the relaxation time for it to reach the point-attractor stability is affected by the collision, or specifically, by the trapping effect of the recirculation flow at the leeside of the upstream dune. Additionally, an excessively strong trapping effect is able to produce the “reversed solitary wave” behavior of barchan dune. The data includes an XLS documenting the collision pattern versus the initial mass ratio for a total of 37 cases, 8 representative collision cases (GIFs and TIFF images), and 8 other selected GIFs.