Relativistic hydrodynamics with momentum-dependent relaxation time

A second order relativistic hydrodynamic theory has been derived using momentum dependent relaxation time in the transport equation. In to do that an iterative technique of gradient expansion approach, namely Chapman-Enskog (CE) particle distribution function employed. The key findings this work are (i) collision term results extended Landau matching condition for thermodynamic variables, (ii) result from numerical solution Boltzmann equation lies somewhere between two popular extreme limits: linear and quadratic ansatz, indicating a fractional power dependence be appropriate, equivalence established method like CE well known moment approach Grad's 14-moment method.