Coupling the dynamics of boundary layers and evolutionary dunes

Area of Science:

• Geomorphology
• Fluid Dynamics
• Computational Science

Background:

• Understanding sand dune evolution requires coupling atmospheric boundary layer dynamics with sediment transport.
• Simulating the vastly different timescales of wind flow and dune change presents a computational challenge.

Purpose of the Study:

• To develop a theoretical framework and numerical method for simulating coupled fluid flow and sediment transport around evolving sand dunes.
• To address the timescale disparity between planetary boundary layer flows and sand dune evolution.
• To validate the numerical approach with existing literature and demonstrate its versatility.

Main Methods:

• Utilized time-dependent curvilinear coordinates to couple atmospheric flow with landform evolution.
• Employed large eddy simulation for the boundary layer and formulated the interface profile as an advection-diffusion equation.
• Adopted a 'severe-wind scenario' to bridge timescale gaps and improve computational efficiency.

Main Results:

• The numerical framework successfully reproduces established scaling laws for sand dune evolution.
• The 'severe-wind scenario' significantly enhances computational efficiency with minimal impact on results.
• The model demonstrates versatility by simulating novel scenarios like sandhole evolution.

Conclusions:

• The developed theoretical and numerical approach provides a robust method for studying aeolian geomorphology.
• The computational strategy effectively handles the multi-scale nature of sand dune dynamics.
• This framework opens new avenues for investigating complex landscape evolution processes.