Origin of the relaxation time in dissipative fluid dynamics

Gabriel S. Denicol, Jorge Noronha, Harri Niemi, Dirk H. Rischke

Research output: Contribution to journalArticlepeer-review


We show how the linearized equations of motion of any dissipative current are determined by the analytical structure of the associated retarded Green's function. If the singularity of Green's function, which is nearest to the origin in the complex-frequency plane, is a simple pole on the imaginary frequency axis, the linearized equations of motion can be reduced to relaxation type equations for the dissipative currents. The value of the relaxation time is given by the inverse of this pole. We prove that, if the relaxation time is sent to zero, or equivalently, the pole to infinity, the dissipative currents approach the values given by the standard gradient expansion.

Original languageEnglish (US)
Article number074019
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number7
StatePublished - Apr 22 2011
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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