Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On Holmboe's instability for smooth shear and density profiles   The linear stability of a stratified shear flow for smooth density profiles
is studied. This work focuses on the nature of the stability boundaries of
flows in which both Kelvin-Helmholtz and Holmboe instabilities are present. For
a fixed Richardson number the unstable modes are confined to finite bands
between a smallest and a largest marginally unstable wavenumber. The results in
this paper indicate that the stability boundary for small wavenumbers is
comprised of neutral modes with phase velocity equal to the maximum/minimum
wind velocity whereas the other stability boundary, for large wavenumbers, is
comprised of singular neutral modes with phase velocity in the range of the
velocity shear. We show how these stability boundaries can be evaluated without
solving for the growth rate over the entire parameter space as was previously
done. The results indicate further that there is a new instability domain that
has not been previously noted in the literature. The unstable modes, in this
new instability domain, appear for larger values of the Richardson number and
are related to the higher harmonics of the internal gravity wave spectrum.

9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con