ABSTRACT: The impact of a nearly cylindrical water mass on a water surface is studied both
experimentally and theoretically. The experiments consist of the rapid release of the
water from the bottom of a cylindrical container suspended above a large water tank and of
the recording of the free-surface shape of the resulting crater with a high speed camera.
A bubble with a diameter of about twice that of the initial cylinder remains entrapped at
the bottom of the crater when the aspect ratio and the energy of the falling water mass
are sufficiently large. Many of the salient features of the phenomenon are explained on
the basis of simple physical arguments. Boundary-integral, potential-flow simulations of
the process are also described. These numerical results are in fair to good agreement with
the observations.
J. Fluid Mech. 294, 181-207, 1995
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