Validity of local thermal equilibrium in anomalous heat diffusion

Boundary conditions of normal and anomalous diffusion from thermal equilibrium.

Infiltration of diffusing particles from one material to another, where the diffusion mechanism is either normal or anomalous, is a widely observed phenomenon. Starting with an underlying continuous-time random-walk model, we derive the boundary conditions for the diffusion equations describing this problem. We discuss a simple method showing how the boundary conditions can be determined from e...

Anomalous heat diffusion.

Consider anomalous energy spread in solid phases, i.e., <Δx(2)(t)>E≡∫(x-E)(2)ρE(x,t)dx∝t(β), as induced by a small initial excess energy perturbation distribution ρE(x,t=0) away from equilibrium. The second derivative of this variance of the nonequilibrium excess energy distribution is shown to rigorously obey the intriguing relation d(2)<Δx(2)(t)>E/dt2=2CJJ(t)/(kBT(2)c), where CJJ(t) equals...

Absence of local thermal equilibrium in two models of heat conduction

A crucial assumption in the conventional description of thermal conduction is the existence of local thermal equilibrium. We test this assumption in two simple models of heat conduction. Our first model is a linear chain of planar spins with nearest neighbour couplings, and the second model is that of a Lorentz gas. We look at the steady state of the system when the two ends are connected to he...

Anomalous refraction of heat flux in thermal metamaterials

Anomalous diffusion in non-equilibrium relativistic heavy-ion rapidity spectra

There is experimental and theoretical evidence that the broad rapidity distribution of net proton yield (p − p) in central heavy-ion collisions at SPS energies could be a signal of non-equilibrium properties of the system. We show that the broad rapidity shape can be well reproduced in the framework of a non-linear relativistic Fokker-Planck dynamics which incorporates non-extensive statistics ...