Compressible air cushioning in liquid-solid impacts

Air cushioning prior to blunt-body impact into
water is considered, with particular focus on investigating the
influence of air compressibility. Building on earlier incompressible
analyses, a local asymptotic model is developed based upon a
thin, viscous, compressible air layer, coupled to an inviscid model
of the water. The parameters for which this model holds are
identified and two compressible regimes are identified. Numerical
results are presented for the weakly compressible case. The
weakly compressible results show that heat is generated in the
gas through a combination of work done compressing the gas
and viscous dissipation. In the pre-impact phase considered, the
temperature is greatest close to the point of touchdown.