“Second Sound” in Solid Helium

Numerical solution of two-dimensional axisymmetric hyperbolic heat conduction

“…According to the HHC model, the thermal energy transport is dominated by wave propagation, rather than diffusion. Experiments demonstrating the wave nature of heat transfer in short time-scale heating and in cryogenic fluids, were reported by Peshkov (1944), Bertman and Sandiford (1970), Tzou (1992), and Mitra et al (1995).…”

“…One of the models describing the heat transfer during short-pulse heating is the hyperbolic heat conduction (HHC) model. This model has been proposed and studied by Cattaneo (1958), Vernotte (1961), Chester (1963), and Bertman and Sandiford (1970). The key of HHC is the introduction of relaxation time, which is the build-up time for the commencement of heat transfer when a temperature gradient has been imposed.…”

Periodic conduction in materials with non-Fourier behaviour

“…A strong impulse to non-Fourier conduction studies was given by modern application of laser heating, where very rapid heat pulses are generated and possible deviation from Fourier law may produce significative differences in heat propagation (see [29][30][31], for example). It should be remarked that, apart few well established results for second sound in liquid He and solids at very low temperatures [32][33][34][35][36], conclusive experimental confirmations of deviation from Fourier law in solids at room temperature are still lacking (see, for example, [37]) although some results for inhomogeneous solids are instead available [38,39].…”

Longitudinal and Transverse Phonon Transport in Dielectric Crystals

“…It still requires ultrasensitive and innovative thermometry to detect arrival/departure of a small amount of energy in a very small scale [1][2][3][4][5], but the relatively slow speed of phonons at cryogenic temperatures significantly reduces the challenges of ultrafast instrumentation as compared to those at room temperature [6]. Dissipation and dispersion mechanisms in phonon transport involves more than the propagation of a single pulse, as observed for second sound in solid helium [1].…”