Related papers: Rychtmyer-Meshkov instability and solid $^4$He mel…
We calculate the dislocation glide mobility in solid $^4$He within a model that assumes the existence of a superfluid field associated with dislocation lines. Prompted by the results of this mobility calculation, we study within this model…
The flux, $F$, carried by solid $^4$He in the range $25.6 - 26.3$ bar rises with falling temperature and at a temperature $T_d$ the flux decreases toward zero. We study $F$ as a function of $^3$He impurity concentration, $\chi$. At…
Solid He4 is viewed as a nearly perfect Debye solid. Yet, recent calorimetry indicates that its low-temperature specific heat has both cubic and linear contributions. These features appear in the same temperature range ($T \sim 200$ mK)…
Molecular dynamics simulation have shown that after initial surface melting, nanowires can melt via two mechanisms: an interface front moves towards the wire centre; the growth of an instability at the interface can cause the solid to…
The dynamic structure factor of superfluid $^4$He has been investigated at very low temperatures by inelastic neutron scattering. The measurements combine different incoming energies resulting in an unprecedentedly large dynamic range with…
We study metastability and nucleation in a kinetic two-dimensional Ising model which is driven out of equilibrium by a small random perturbation of the usual dynamics at temperature T. We show that, at a mesoscopic/cluster level, a…
Torsional oscillator experiments show evidence of mass decoupling in solid 4He. This decoupling is amplitude dependent, suggesting a critical velocity for supersolidity. We observe similar behavior in the elastic shear modulus. By measuring…
I present here a microscopic theory for the superfluidity of $^4$He (He II) derived from experiments, and answer its essential questions. With a "momenton" model, the superfluid is shown to feature as a "harmonic superfluid". In which a new…
This work is devoted to the study of the influence of temperature anisotropy and parallel heat flux on the stability of supersonic shear flow in collisionless plasmas. Within a fluid-based framework, we employ the 16-moment transport…
We show that the interaction of a particle with a directionally solidified interface induces the onset of morphological instability provided that the particle-interface distance falls below a critical value. This instability occurs at…
Boundary conditions for the solid-liquid interface of the solidifying pure melt have been derived. In the derivation the model of Gibbs interface is used. The boundary conditions include both the state quantities of bulk phases are taken at…
At pressure $\sim$ 25.7 bar the flux, $F$, carried by solid \4he for $T >$ 100 mK depends on the net chemical potential difference between two reservoirs in series with the solid, $\Delta \mu$, and obeys $F \sim (\Delta \mu)^b$, where $b…
Experiments show that all the derivatives of the thermo-physical variables are nearly constant. The constant value of the derivatives indicates linear relationship between the variables. Neither the volume coefficient of thermal expansion…
We studied a novel cooling method, in which $^3$He and $^4$He are mixed at the $^4$He crystallization pressure at temperatures below $0.5\,\mathrm{mK}$. We describe the experimental setup in detail, and present an analysis of its…
We review the anomalous behavior of solid He-4 at low temperatures with particular attention to the role of structural defects present in solid. The discussion centers around the possible role of two level systems and structural glassy…
We have re-examined the Andreev-Lifshitz theory of supersolids. This theory implicitly neglects uniform bulk processes that change the vacancy number, and assumes an internal pressure $P$ in addition to lattice stress $\lambda_{ik}$. Each…
We present a linear stability analysis of the perturbation modes in anisotropic MHD flows with velocity shear and strong magnetic field. Collisionless or weakly collisional plasma is described within the 16-momentum MHD fluid closure model,…
Using Andreev and Lifshitz's supersolid hydrodynamics, we obtain the propagating longitudinal modes at non-zero applied pressure $P_{a}$ (necessary for solid 4He), and their generation efficiencies by heaters and transducers. For small…
Radiative cooling can drive dynamics in multi-phase gas. A dramatic example is hydrodynamic `shattering', the violent, pressure-driven fragmentation of a cooling cloud which falls drastically out of pressure balance with its surroundings.…
We perform direct numerical simulations of three dimensional Rayleigh-Taylor turbulence with a nonuniform singular initial temperature background. In such conditions, the mixing layer evolves under the driving of a varying effective Atwood…