Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relativistic expansion of a magnetized fluid   We study semi-analytical time-dependent solutions of the relativistic
magnetohydrodynamic (MHD) equations for the fields and the fluid emerging from
a spherical source. We assume uniform expansion of the field and the fluid and
a polytropic relation between the density and the pressure of the fluid. The
expansion velocity is small near the base but approaches the speed of light at
the light sphere where the flux terminates. We find self-consistent solutions
for the density and the magnetic flux. The details of the solution depend on
the ratio of the toroidal and the poloidal magnetic field, the ratio of the
energy carried by the fluid and the electromagnetic field and the maximum
velocity it reaches.

23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin