Temperature Variation in the Dark Cosmic Fluid in the Late Universe

Abstract

A one-component dark energy fluid model of the late universe is considered ($w<-1$) when the fluid, initially assumed laminar, makes a transition into a turbulent state of motion. Spatial isotropy is assumed so that only the bulk viscosities are included ($\zeta$ in the laminar epoch and ${\zeta }_{\mathrm{turb}}$ in the turbulent epoch). Both viscosities are assumed to be constants. We derive a formula, new as far as we know, for the time dependence of the temperature $T(t)$ in the laminar case when viscosity is included. Assuming that the laminar/turbulent transition takes place at some time $t_s$ before the big rip is reached, we then analyze the positive temperature jump experienced by the fluid at $t=t_{\ast }$ if ${\zeta }_{\mathrm{turb}}>\zeta$. This is just as one would expect physically. The corresponding entropy production is also considered. A special point emphasized in the paper is the analogy that exists between the cosmic fluid and a so-called Maxwell fluid in viscoelasticity.

16 pages latex, no figures, to appear in Mod. Phys. Lett. A. Note: this file was previously posted incorrectly as arXiv:1509.06995v2

References in corpus (6)

• Dissipation of dark matter
• Turbulence and Little Rip Cosmology
• Quasi-Rip: A New Type of Rip Model without Cosmic Doomsday
• Viscosity-Induced Crossing of the Phantom Barrier
• On Isotropic Turbulence in the Dark Fluid Universe
• Friction forces in cosmological models

Cited by in corpus (4)

• General Bulk-Viscous Solutions and Estimates of Bulk Viscosity in the Cosmic Fluid
• Remarks on cosmological bulk viscosity in different epochs
• Can the Hubble tension be resolved by bulk viscosity?
• Study of a viscous $\Lambda$WDM model: Near equilibrium condition, entropy production, and cosmological constraints