Expansion of Hadronic Bubbles During the Cosmological Quark-Hadron Transition

The structure of hydrodynamical flow produced by an expanding hadronic bubble during a first-order quark-hadron phase transition is discussed. Numerical results are presented characterizing the bubble growth from the initial nucleation time onwards. The hydrodynamical equations in combination with the junction conditions imposed at the interface are presented. It is found that the effect of long-range energy transport by neutrinos becomes important when the bubble radius approaches the neutrino mean free path of about 1 cm. However, it is possible that the mean distance between bubble nucleation sites might be smaller than this, so that bubble coalescence would occur before neutrino transport becomes important.