A comparison of momentum transport models for numerical relativity

Understand

The main problems of nonvacuum numerical relativity, compact binary mergers and stellar collapse, involve hydromagnetic instabilities and turbulent flows, so that kinetic energy at small scales have mean effects at large scale that drive the secular evolution.

• Notable among these effects is momentum transport.
• We investigate two models of this transport effect, a relativistic Navier-Stokes system and a turbulent mean stress model, that are similar to all of the prescriptions that have been attempted to date for treating subgrid effects on binary neutron star mergers and their aftermath.
• Our investigation involves both stability analysis and numerical experimentation on star and disk systems.