Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hydrodynamics of crystals with interstitials   The hydrodynamic equations for a crystals with interstitials, taking into
account the dissipative processes of the viscosity, heat conduction and the
interstitial diffusion are derived. To achieve that we use the phenomenological
approach has originally been applied in the theory of the superfluids for the
derivation of equations of the two-fluid hydrodynamics. On the basis of the
obtained equations the problem of the propagation of plane waves in the
crystals with low interstitial concentration has been considered. For the case
when effects of the viscosity and the heat conduction are absent and the
diffusion mobility of interstitials is small the absorption coefficient of
longitudinal sound wave has been calculated.

27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
16
The categories of this paper are: stat