A nonsimilar solution for blast waves by an asymptotic piston expansion

An analytical technique is outlined for predicting the blast wave from a rapid but asymptotic expansion of an inner piston-like surface. The method more accurately describes real blasts compared to conventional point source models and agrees favorably with the exact method of characteristic solution for wave Mach numbers exceeding approximately 1.1. The method makes two a priori assumptions: (1) that the blast wave density can be described by a power law, and (2) that an equation exists for the motion of the driving piston. The present treatment extends the work of Bach and Lee, who assume a zero radius piston (i.e., a point source).