Numerical simulation of three-dimensional wind flow patterns over a star dune

In this paper, three-dimensional wind flow patterns over a star dune under a longitudinal (W, 270°) and transverse airflow (ENE, 70°) were examined using computational fluid dynamics (CFD) simulations. New surveying techniques of airborne LiDAR and DGPS allow for establishment of the realistic digital model of the star dune. Simulation results were then validated by field measurement using three-dimensional (3D) ultrasonic anemometers combined with arrays of HOBO cup anemometers. Results show that incident flow conditions (longitudinal or transverse airflow) controlled by the angle between incident flow and dune crestline exert great impact on wind flow patterns over the star dune. In periods of longitudinal airflow, a marked feature of wind flow pattern was flow deflection. Wind erosion occurs on both sides of WNW and S sides during W wind and its main effect was to prolong the star dune longitudinally. However, leeside flow separation and reversal were obvious under transverse airflow. The main effect of ENE wind was to promote the upward growth of the star dune. The CFD simulation of 3D wind flows over complex dune system presents great potential for geomorphological research, enabling new insights into complex dune geomorphology and dynamics.