Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stability of Plane-Parallel Vibrational Flow In a Two-Layer System   The stability of the interface separating two immiscible incompressible
fluids of different densities and viscosities is considered in the case of
fluids filling a cavity which performs horizontal harmonic oscillation. There
exists a simple basic state which corresponds to the unperturbed interface and
plane-parallel unsteady counter flows; the properties of this state are
examined. A linear stability problem for the interface is formulated and solved
a) for both inviscid and b) for both viscous fluids. A transformation is found
which reduces the linear stability problem under inviscid approximation to the
Mathieu equation. The parametric resonant regions of instability associated
with the intensification of capillary-gravity waves at the interface are
examined and the results are compared to those found in the viscous case in a
fully numerical investigation.

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The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio