Role of Transverse Displacements in the Formation of Subaqueous Barchan Dunes.

  title={Role of Transverse Displacements in the Formation of Subaqueous Barchan Dunes.},
  author={Carlos A. Alvarez and E. Franklin},
  journal={Physical review letters},
  volume={121 16},
Crescentic shape dunes, known as barchan dunes, are formed by the action of a fluid flow on a granular bed. These bedforms are common in many environments, existing under water or in air, and being formed from grains organized in different initial arrangements. Although they are frequently found in nature and industry, details about their development are still to be understood. In a recent paper [C. A. Alvarez and E. M. Franklin, Phys. Rev. E 96, 062906 (2017)PRESCM2470-004510.1103/PhysRevE.96… Expand
Horns of subaqueous barchan dunes: A study at the grain scale.
Focusing on moving grains whose initial positions were on the horns, it is shown that their residence time and traveled distance are related following a quasilinear relation, which provides new insights into the physical mechanisms underlying the shape of barchan dunes. Expand
Shape evolution of numerically obtained subaqueous barchan dunes.
The present paper reproduces numerically the shape evolution of barchans from their initiation until they have reached a stable shape, and computed the bed evolution by using the computational fluid dynamics-discrete element method with large eddy simulation for the same initial and boundary conditions of experiments. Expand
Force distribution within a barchan dune
Barchan dunes, or simply barchans, are crescent-shaped dunes found in diverse environments such as the bottom of rivers, Earth’s deserts and the surface of Mars. In a recent paper [Phys. Rev. E 101,Expand
Velocity fields and particle trajectories for bed load over subaqueous barchan dunes
This paper presents an experimental investigation of moving grains over subaqueous barchan dunes that consisted of spherical glass beads of known granulometry. Prior to each test run, aExpand
Experimental study on the stable morphology and self-attraction effect of subaqueous barchan dunes
Abstract The evolutionary process of isolated dunes under the action of a unidirectional steady water flow is recorded from a bottom-up visual angle by optical synchronization imaging measurements.Expand
A Comprehensive Picture for Binary Interactions of Subaqueous Barchans
We investigate experimentally the short-range interactions occurring between two subaqueous barchans. The experiments were conducted in a water channel of transparent material where controlled grainsExpand
Growth of barchan dunes of bidispersed granular mixtures
Barchans are dunes of crescentic shape found on Earth, Mars and other celestial bodies, growing usually on polydisperse granular beds. In this Letter, we investigate experimentally the growth ofExpand
Wake Induced Long Range Repulsion of Aqueous Dunes.
Experimental evidence is presented that aqueous dunes interact over large distances without the necessity of exchanging mass, and mediated by turbulent structures forming in the wake of a dune, and lead to dune-dune repulsion, which can prevent collisions. Expand
Morphodynamics of Barchan‐Barchan Interactions Investigated at the Grain Scale
Corridors of size-selected crescent-shaped dunes, known as barchans, are commonly found in water, air, and other planetary environments. The growth of barchans results from the interplay between aExpand
Secondary Flows and Vortex Structure Associated With Isolated and Interacting Barchan Dunes
  • N. R. Bristow, G. Blois, J. Best, K. T. Christensen
  • Geology
  • 2020


Birth of a subaqueous barchan dune.
The formation of subaqueous barchan dunes from initially conical heaps in a rectangular channel is reported, showing the existence of the time scales 0.5t_{c} and 2.5T_{c] for the appearance and equilibrium of horns, respectively. Expand
Subaqueous barchan dunes in turbulent shear flow. Part 1. Dune motion
Experiments are reported on the formation and migration of isolated dunes in a turbulent channel flow. These dunes have a very robust crescentic shape with horns pointing downstream, very similar toExpand
On the genesis and evolution of barchan dunes: morphodynamics
Barchan dunes are crescent-shaped formations of sand that can dominate both desert and subaqueous landscapes when the supply of sand is scarce. Because of the complexity and scale of the underlyingExpand
Minimal size of a barchan dune.
The size and the shape of the minimal barchan dune depend on the wind friction speed and the sand flux on the area between dunes in a field, and the rate at which grains enter saltation on Mars is one order of magnitude higher than on Earth, and is relevant to correctly obtain the minimal dune size on Mars. Expand
Field evidence for surface-wave-induced instability of sand dunes
It is found that dune collisions and changes in wind direction destabilize the dunes and generate surface waves on the barchans, which plays a fundamental role in the control of size selection and the development of dune patterns. Expand
Corridors of barchan dunes: Stability and size selection.
Barchans are crescentic dunes propagating on a solid ground. They form dune fields in the shape of elongated corridors in which the size and spacing between dunes are rather well selected. We showExpand
A scaling law for aeolian dunes on Mars, Venus, Earth, and for subaqueous ripples
Abstract The linear stability analysis of the equations governing the evolution of a flat sand bed submitted to a turbulent shear flow predicts that the wavelength λ at which the bed destabilises toExpand
On the crescentic shape of barchan dunes
Abstract.Aeolian sand dunes originate from wind flow and sand bed interactions. According to wind properties and sand availability, they can adopt different shapes, ranging from huge motion-less starExpand
The shape of barchan dunes
Barchans are crescent-shaped sand dunes forming in arid regions with unidirectional wind and limited sand supply. We report analytical and numerical results for dune shapes under differentExpand
Selection of dune shapes and velocities Part 1: Dynamics of sand, wind and barchans
Abstract:Almost fifty years of investigations of barchan dunes morphology and dynamics is reviewed, with emphasis on the physical understanding of these objects. The characteristic quantitiesExpand