Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relativistic Dynamics of Non-ideal Fluids: Viscous and heat-conducting
  fluids I. General Aspects and 3+1 Formulation for Nuclear Collisions   Relativistic non-ideal fluid dynamics is formulated in 3+1 space--time
dimensions. The equations governing dissipative relativistic hydrodynamics are
given in terms of the time and the 3-space quantities which correspond to those
familiar from non-relativistic physics. Dissipation is accounted for by
applying the causal theory of relativistic dissipative fluid dynamics. As a
special case we consider a fluid without viscous/heat couplings in the causal
system of transport/relaxation equations. For the study of physical systems we
consider pure (1+1)-dimensional expansion in planar geometry, (1+1)-dimensional
spherically symmetric ({\em fireball}) expansion, (1+1)-dimensional
cylindrically symmetric expansion and a (2+1)-dimensional expansion with
cylindrical symmetry in the transverse plane ({\em firebarell} expansion). The
transport/relaxation equations are given in terms of the spatial components of
the dissipative fluxes, since these are not independent. The choice for the
independent components is analogous to the non-relativistic equations.

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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: cs
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The categories of this paper are: funct-an
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph