| Full text | |
| Author(s): |
Assis, W. R.
;
Franklin, E. M.
;
Vriend, N. M.
Total Authors: 3
|
| Document type: | Journal article |
| Source: | JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE; v. 130, n. 2, p. 15-pg., 2025-02-01. |
| Abstract | |
Sand dunes are ubiquitous in nature, and are found in abundance on Earth and other planetary environments. One of the most common types are crescent-shaped dunes known as barchans, whose mid-line could be assumed to behave as 2D dunes. In this work, we (a) compare the morphology of the mid-line of 3D barchans with 2D dunes; and (b) track the evolution of 3D barchans and 2D dunes while reversing flow conditions. We performed experiments on 2D dunes in a 2D flume and Euler-Lagrange simulations of 3D bedforms. In all reversal experiments and simulations, the initial condition starts with a conical heap being deformed into a steady-state dune, which is then perturbed by reversing the flow, resulting in an inverted dune. We show that during the reversal the grains on the lee side immediately climb back onto the dune while its internal part and toe remain static, forming a new lee face of varying angle on the previous stoss slope. We show that (a) the characteristic time for the development of 2D dunes scales with that for 3D barchans, (b) that the time for dune reversal is twice the time necessary to develop an initial triangular or conical heap to steady-state, and (c) that a considerable part of grains remain static during the entire process. Our findings reveal the dynamics for dune reversal, and highlight that numerical computations of barchans based on 2D slices, which are more feasible in geophysical scales, predict realistic outcomes for the relevant time-scales. (AU) | |
| FAPESP's process: | 21/12910-8 - Segregation of polydisperse particles during dune-dune interaction |
| Grantee: | Willian Righi Assis |
| Support Opportunities: | Scholarships abroad - Research Internship - Doctorate (Direct) |
| FAPESP's process: | 19/10239-7 - Bed-load instabilities: granular dynamics and interaction with the fluid flow |
| Grantee: | Willian Righi Assis |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |
| FAPESP's process: | 18/14981-7 - Modeling of dense granular flows: experiments, numerical simulations and stability analyses |
| Grantee: | Erick de Moraes Franklin |
| Support Opportunities: | Research Grants - Young Investigators Grants - Phase 2 |