Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electrostrictive fluid pressure from a laser beam   Recent times have seen surge of research activity on systems combining fluid
mechanics and electromagnetic fields. In radiation optics, whenever information
about the distribution of pressure in a dielectric fluid is required, the
contribution from electrostriction becomes important. In the present paper we
calculate how the local pressure varies with position and time when a laser
beam is imposed in a uniform fluid. A Gaussian intensity profile of arbitrary
time dependence is assumed for the beam, and general results are derived in
this case. For demonstration we analyze two different cases: first, that the
beam is imposed suddenly (mathematically in the form of a step function);
secondly, that the beam is switched on in a soft way. In both cases, simple
analytical expressions for the pressure distribution are found.

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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math