Mechanical Model for Relativistic Blast Waves

Relativistic blast waves can be described using a mechanical model. In this model, the "blast"—the compressed gas between the forward and reverse shocks—is viewed as one hot body. Equations governing its dynamics are derived from the conservation of mass, energy, and momentum. Simple analytical solutions are obtained in the two limiting cases of an ultrarelativistic and a nonrelativistic reverse shock. Equations are derived for the general explosion problem.