  We study the radial expansion of cylindrical tubes in a hot QGP. These tubes
are treated as perturbations in the energy density of the system which is
formed in heavy ion collisions at RHIC and LHC. We start from the equations of
relativistic hydrodynamics in two spatial dimensions and cylindrical symmetry
and perform an expansion of these equations in a small parameter, conserving
the nonlinearity of the hydrodynamical formalism. We consider both ideal and
viscous fluids and the latter are studied with a relativistic Navier-Stokes
equation. We use the equation of state of the MIT bag model. In the case of
ideal fluids we obtain a breaking wave equation for the energy density
fluctuation, which is then solved numerically. We also show that, under certain
assumptions, perturbations in a relativistic viscous fluid are governed by the
Burgers equation. We estimate the typical expansion time of the tubes.
