08 Dec 2023
 | 08 Dec 2023

Barchan swarm dynamics from a Two-Flank Agent-Based Model

Dominic T. Robson and Andreas C. W. Baas

Abstract. We perform simulations of barchan swarms using the Two-Flank Agent-Based model investigating the effects of changing the angular separation between primary and secondary modes of wind, the density at which new dunes are injected, and the parameter qshift which controls the rate at which sediment is reorganised to restore symmetry in an asymmetric dune. Unlike previous agent-based models, we are able to produce longitudinally homogeneous size distributions and, for sparse swarms, steady longitudinal number density. We are able to constrain qshift by comparing the range of values for which longitudinally stability is observed with the range of values for which the width of asymmetry distributions is consistent with real-world swarms. Furthermore, we demonstrate dune size, asymmetry, dune density, spatial alignment, and collision dynamics are all strongly influenced by the angular separation of bimodal winds.

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Dominic T. Robson and Andreas C. W. Baas

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2023-2900', Michael Marvin, 23 Dec 2023
  • RC1: 'Comment on egusphere-2023-2900', Anonymous Referee #1, 30 Mar 2024
  • RC2: 'Comment on egusphere-2023-2900', Anonymous Referee #2, 01 Apr 2024
  • AC1: 'Final Author Comments on egusphere-2023-2900', Dominic Robson, 25 Apr 2024
Dominic T. Robson and Andreas C. W. Baas

Model code and software

DTRobson/TwoFlankABModel: TwoFlankBarchanABMv2 Dominic Robson

Video supplement

Barchan Swarm Simulations Using the Two-Flank Agent-Based Model Dominic Robson

Dominic T. Robson and Andreas C. W. Baas


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Short summary
We present simulations of large populations (swarms) of a type of sand dune known as barchans. Our findings reveal that the rate at which sand moves inside an asymmetric barchan is vital to the behaviour of swarms and that many observed properties of the dunes can be explained by similar rates. We also show that different directions of the wind and the density of dunes added to swarms play important roles in shaping their evolution.