- 1Ben-Gurion University of the Negev, Department of Environmental, Geoinformatics and Urban Planning Sciences, Beer-Sheva, Israel (sabal@post.bgu.ac.il)
- 2Department of Ocean Engineering, Texas A&M University, College Station, TX, USA
- 3Leipzig University, Institute for theoretical Physics, Faculty of Physics and Earth System Sciences, Germany
- 4Department of Solar Energy and Environmental Physics, Ben-Gurion University of the Negev, Be’er Sheva, Israel
This study investigates the mechanisms of aeolian (wind) ripple formation through controlled experiments in the open-circuit boundary wind tunnel at Ben-Gurion University, focusing on how interactions between different grain sizes and wind velocities influence the development and evolution of impact and aerodynamic ripples.
We measured ripple morphology, including wavelength and sinuosity, using 3D scanning (EinScan Pro HD) and time-lapse photography, and analyzed the vertical sand flux, using an array of saltation traps. These measurements were conducted across various wind velocities (u* = 0.22-0.9 m/s) with glass beads and natural dune sands with median grain sizes of d50 = 90, 170, 230, 248, and 375 µm. We observed distinct differences in ripple formation patterns by systematically altering these parameters.
The results reveal distinct ripple regimes and transitions driven by grain size and wind velocity. For fine-grain sand beds, two ripple scales emerged: smaller (λ = 0.3-3 cm) linear impact ripples superimposed on the larger (λ = 5-55 cm) aerodynamic ripples. Increasing wind velocity led to the disappearance of impact ripples and transformed the aerodynamic ripples into more complex wavy patterns with higher sinuosity (SI = 1.28-1.74). These aerodynamic ripples share morphological similarities with current (subaqueous) ripples, particularly in terms of their increased sinuosity and development stages, supporting that their origin is due to hydrodynamic instability (Yizhaq et al., 2024). In comparison, coarser grains produced only one-scale regular impact ripple with lower sinuosity (SI ≈ 1), and their wavelength increased with wind velocity.
Sand flux measurements revealed a nonlinear relationship with wind velocity in agreement with Martin and Kok, 2017 formulation, demonstrated the critical influence of grain size on transport rates, and can offer insights into sediment transport mechanisms and existing sediment transport models.
By distinguishing between aerodynamic and impact regimes and spatiotemporal dynamics, we provide a fresh look at ripple formation in terrestrial and extraterrestrial environments, including the debated origins of the large Martian ripples.
How to cite: saban, L., katra, I., Durán, O., Rein, C., Kroy, K., and Yizhaq, H.: Aerodynamic and Impact ripple dynamics: The influence of grain size and wind velocity on morphology and sand flux., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10467, https://doi.org/10.5194/egusphere-egu25-10467, 2025.
