Direct observation of shock splitting in a vapor–liquid system

The splitting of a single liquefaction shock wave into a vapor‐phase forerunner shock and a following condensation shock is observed photographically in shock‐tube experiments. The behavior of the two‐shock system is qualitatively described by equilibrium shock conditions, but the state downstream of the forerunner shock is found to be far from equilibrium. It is proposed that this state is limited by the critical supersaturation for homogeneous nucleation. The overall pressure jump for the two‐shock system is much greater than would be predicted by an equilibrium calculation.