RICH

 

Moving Mesh Hydrodynamics

UPDATE: The parallel 3D version is now up! It is still not too user friendly, so if you are intrested contact me and I'll be happy to help with it.

RICH (Racah Institute Computational Hydrodynamics) is a Voronoi based moving mesh code that I co-developed along with Almog Yalinewich. Our code is open source and available at github. We are currently finishing the 3D version of the code, which will be stable soon. Since Voronoi based codes are relatively new, it might take some time for a new user to understand how to correctly use them. Feel free to contact me with any question about how to run/install/customize our code.

Pressure Based Load Balancing

Pressure Based Load Balancing

 

More Accurate Moving Mesh

 
 

G2 Cloud

Ignition of detonation in accreted helium envelopes

 

Are the Largest Asteroids Primoridal?

 

The last stages of terrestrial planet formation are relatively uncertain. The predominate theory advocates a series of giant impacts between planetary embryos, which naturally leads to terrestrial planets having a slow spin. A competing theory suggests that terrestrial planets formed by forming a semi-collisional disk around them and accreting it, resulting in terrestrial planets having a relatively fast spin. Discriminating between the two theories is hard since in our solar system there are only four terrestrial planets. However, the largest asteroids have undergone the same formation mechanism as the terrestrial planets and can be used to help better understand how planets form. A caveat to this approach is that asteroids undergo mutual collisions inside the Main Belt and thus their spins might be altered during their lifetime. We show that under a few simplifying assumptions the spin distribution of asteroids is a Levy flight (a distribution characterized by a power law tail) and that there were not enough collisions to explain the observed spin rates. Since the largest asteroids spin relatively fast, this suggests that the formation of terrestrial planets involves some semi-collisional accretion.

Histogram of spins for the largest asteroids. The red line is the theoratical expectation from collisions during the lifetime of the solar system.

The Multi-Dimensional Structure of Radiative Shocks

 

Radiative shocks, behind which gas cools much faster than the dynamical time, play a key role in a range of astrophysical transients, including classical novae, young supernovae (SNe) interacting with circumstellar material (e.g.~SNe IIn), and binary star mergers. These shocks are susceptible to several instabilities (e.g. NTSI). We show that these instabilities reduce the effective temperature of the emitted radiation as well as potentially serve as an acceleration ground for high energy ions. Link to movies section.