Dissipative fluid dynamics for the dilute Fermi gas at unitarity: Free expansion and rotation

Understand

We investigate the expansion dynamics of a dilute Fermi gas at unitarity in the context of dissipative fluid dynamics.

• Our aim is to quantify the effects of shear viscosity on the time evolution of the system.
• We compare exact numerical solutions of the equations of viscous hydrodynamics to various approximations that have been proposed in the literature.
• Our main findings are: i) Shear viscosity leads to characteristic features in the expansion dynamics; ii) a quantitative description of these effects has to include reheating; iii) dissipative effects are not sensitive to the equation of state P(n,T) as long as the universal relation P=(2/3)E is satisfied; iv) the expansion dynamics mainly constrains the cloud average of the shear viscosity.