  Using hydrodynamic computer codes, we study the possible patterns of
relativistic expansion of an enormous pair-electromagnetic-pulse (P.E.M.
pulse); a hot, high density plasma composed of photons, electron-positron pairs
and baryons deposited near a charged black hole (EMBH). On the bases of
baryon-loading and energy conservation, we study the bulk Lorentz factor of
expansion of the P.E.M. pulse by both numerical and analytical methods.
