WIND SCULPTING OF PLANETARY SURFACES: CONSTRAINTS FROM SIMULATIONS AND PHYSICAL EXPERIMENTS ON AEOLIAN LANDSCAPES OF THE ARGENTINIAN PUNA

Wind erosion and deposition plays an important role in the geomorphologic evolution of many planetary surfaces in the Solar System. Earth analogs are crucial to providing constraints on the processes and dynamics that shape aeolian bedrock landscapes, and the Argentinean Puna contains a unique combination of wind abrasional and depositional landforms such as yardangs, megaripples, and periodic bedrock ridges and dunes, that serves as a perfect natural laboratory to compare with arid planets like Mars. As part of a long-term effort to understand the processes that shape these landforms in Argentina, we have embarked on an effort to combine field work, with physical and numerical experiments to quantify how bedrock topography affects local flow fields and potential sediment transport pathways. Here we report on our preliminary results from wind tunnel experiments and heuristic numerical simulations using computational fluid dynamics software and high-resolution topography.

Topography of yardangs, periodic bedrock-ridges, and megaripples were created using Structure-from-Motion (SfM) techniques applied to photogrammetric surveys using both drone video footage and ground-based still photography. We use the resultant high-resolution 3D surface meshes with Autodesk Flow Design, a computational fluid dynamics software, to visualize the three-dimensional flow field and delineate the pressure and velocity fields around each respective landform. We also conducted simulations to compare with the results of wind tunnel experiments using a full-scale model of a megaripple. These results were then compared with our field observations and measurements.

Numerical model results show a strong correspondence to wind tunnel experiments, and provide insight into how yardang and mega-ripple topography induce distinctly complex flow dynamics that can affect sediment transport pathways and local abrasion patterns. The simulations generally support current knowledge of windflow over complex terrain, but also suggest some nuances that help explain field observations. We will present results for several simulations and discuss problems and pitfalls that will inform our continuing efforts.