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Asteroids

I study weirdly shaped rubble-pile or granular asteroids. By 'study' I mean that I try to understand the mechanical/dynamical behavior of these asteroids and not so much their chemical, mineralogical, or albedo properties. 

These asteroids often display several interesting geophysical phenomena like segregation, avalanching, and mass shedding. These have been observed by different asteroid missions, namely the Hayabusa I and II by JAXA and the OSIRIS-REx by NASA to Itokawa, Ryugu, and Bennu, respectively.

 

Check out our recent paper on continuum modeling of top-shaped asteroids published in the Proceedings of the Royal Society A here!

I modified the open-source Soft Sphere DEM code called LAMMPS to investigate the motion of grains on rotating and self-gravitating axisymmetric shapes.

The main aim behind this was to be able to verify the efficacy of our theoretical model as DEM is very computationally expensive. Besides capturing the major phenomena the DEM results showed a good match with the theory. Here you may find the details of the work done using DEM.

I also wrote a bit on explaining in simple words what DEM is, you may find it on my blog here.

Discrete Element Method

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Shallow Avalanche Theory

Following the depth-averaged shallow granular flow theory over complex basal topographies developed by Gray and Hutter in 1999 which in itself is an extension of the popular shallow-water theory, our group developed a model to study regolith motion on small planetary bodies.

These scenarios are interesting because asteroids have non-uniform gravitational fields, they are rotating (mostly with varying spin rates) and they have undulating surfaces. 

Using this theory we were able to justify several physical features observed on these asteroids, for example, the segregation pattern on Itokawa. Find our recent paper in the Journal of Fluid Mechanics here.

Meridional circulation in stars

I currently work on meridional circulation in stellar atmospheres with Kristen Menou at the University of Toronto. We use tools of atmospheric sciences to better understand the effect of mean-molecular weight gradient in the atmosphere, using analytics, numerics, and computation.