Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Turbulence in a stably stratified fluid: Onset of global anisotropy as a
  function of the Richardson number   It is necessary to introduce an external forcing to induce turbulence in a
stably stratified fluid. The Heisenberg eddy viscosity technique should in this
case suffice to calculate a space-time averaged quantity like the global
anisotropy parameter as a function of the Richardson number. We find
analytically that the anisotropy increases linearly with the Richardson number,
with a small quadratic correction. A numerical simulation of the complete
equations shows the linear behaviour.

16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an