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Published on: February 13, 2018
Numerical modeling of the wind flow over a transverse dune
Ascânio D Araújo1, Eric J R Parteli, Thorsten Pöschel
1Departamento de Física, Universidade Federal do Ceará, Campus do Pici, 60451-970 Fortaleza, Ceará, Brazil.
Scientific Reports
|October 5, 2013
Summary
Transverse dunes are found across the solar system. Numerical simulations reveal that the separation bubble behind dunes grows with wind shear velocity, influencing sand transport direction and dune migration.
Area of Science:
- Planetary Science
- Fluid Dynamics
- Geomorphology
Background:
- Transverse dunes exhibit a fixed profile perpendicular to unidirectional winds.
- These dunes are observed on various celestial bodies within our solar system.
- Understanding wind flow dynamics over dunes is crucial for predicting their evolution.
Purpose of the Study:
- To numerically investigate the turbulent wind flow over a transverse dune.
- To analyze the characteristics of the separation bubble and its dependence on wind shear velocity.
- To determine the conditions for reverse sediment transport within the separation bubble.
Main Methods:
- Computational fluid dynamics (CFD) simulations were employed.
- The study focused on the average turbulent wind flow.
- Simulations analyzed the dune lee and the separation bubble dynamics.
Main Results:
- The separation bubble length shows a strong dependence on wind shear velocity (u).
- Bubble length is nearly constant for u between 0.2-0.8 m/s, then increases linearly with u.
- Reverse sediment transport requires u > 0.39 m/s and initiation requires u ≈ 0.49 m/s.
Conclusions:
- Wind shear velocity is a critical factor governing separation bubble size and sediment transport direction.
- These findings have implications for understanding dune dynamics on Earth and other planets.
- The study provides quantitative thresholds for reverse sediment transport, impacting dune migration models.
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