Viscous avalanches on a spherical minor planet

¹ Department of Physics, University of Toronto, Canada
² Indian Institute of Technology Kanpur, India

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Published online: 1 December 2025

Abstract

Granular avalanches influence the surface evolution of small celestial bodies such as asteroids and moons. Understanding their dynamics is crucial for interpreting surface features observed by space missions. We adapt a depth-averaged shallow water model to simulate granular avalanches on a rotating, gravitating sphere, building on prior work by Gaurav et al. (2021) and Banik et al. (2022). Using the pseudo-spectral Dedalus code, we explore first-order granular motion by varying material friction and rotational speed. We simulate Gaussian hills of yielded material flowing under Coriolis forces. A limitation of our approach, like other spherical shallow water models, is inaccuracy near the poles, though results remain largely unaffected. Our findings provide benchmarks for future, more complex models incorporating spin change, thermal effects, and collisions.