
The energy-momentum tensor of a perfect fluid contains only the diagonal components.
In
physics, a 'perfect fluid' is a
fluid that can be completely characterized by its rest frame
energy density ρ and ''isotropic''
pressure ''p''.
Real fluids are "sticky" and contain (and conduct) heat. Perfect fluids are idealized models in which these possibilities are neglected. Specifically, perfect fluids have no
shear stresses,
viscosity, or
heat conduction.
In tensor notation, the
energy-momentum tensor of a perfect fluid can be written in the form
:
where ''U'' is the
velocity vector field of the fluid and where
is the metric tensor of
Minkowski spacetime.
Perfect fluids admit a
Lagrangian formulation, which allows the techniques used in field theory to be applied to fluids. In particular, this enables us to
quantize perfect fluid models. This Lagrangian formulation can be generalized, but unfortunately, heat conduction and anisotropic stresses cannot be treated in these generalized formulations.
Perfect fluids are often used in
general relativity to model idealized distributions of
matter, such as in the interior of a star.
See also
★
equation of state
★
ideal gas
★
fluid solutions in general relativity
References
★ The Large Scale Structure of Space-Time, by S.W.Hawking and G.F.R.Ellis, Cambridge University Press, 1973. ISBN 0-521-20016-4, ISBN 0-521-09906-4 (pbk.)
External links
★ Mark D. Roberts, [A Fluid Generalization of Membranes http://www.arXiv.org/abs/hep-th/0406164 hep-th/0406164].
''Note:'' Mark Roberts is an occasional
Wikipedia editor Markdroberts. He contributed to this article.