The blast wave caused by a localized release of energy in a gas has
become a textbook hydrodynamics problem since the seminal work of Taylor, von
Neumann and Sedov. Yet, it has received very little attention at the kinetic level,
which can provide a complementary range of insights: notably, transient regimes
and the microscopic structure of the shock front, reduced to a singular boundary
in continuum equations. As a first step, we study blast waves in a one-dimensional
gas of hard particles. This simple limit helps develop important intuitions
pertaining to any type of blast, and it is amenable to kinetic analysis { even
with the addition of energy dissipation leading to "snowplow" dynamics, or an
inhomogeneous mass repartition (as found in astrophysical systems and granular
materials). Furthermore, the conservative case proves to be of remarkable interest,
in demonstrating subtle aspects of dimensional analysis and their resolution
through microscopic insights: we show that it can effectively behave like a zero-
dimensional system, reduced to the shock front, depending on whether a length
scale appears in the initial mass distribution


Supplementary Materials: