On modelling fluid/body interactions, impacts and lift-offs

A description is given of recent progress in the understanding of mechanisms in fluid-body interactions where the motion of a body and the motion of the surrounding fluid affect each other substantially. The mathematical modelling of such unsteady interactions is for internal channel and external near-wall flows in two spatial dimensions and time. The emphasis throughout is on analytical developments with accompanying reduced computation. The successive aspects studied here are interactions and impacts in inviscid flows, skimming and sinking, the lift-off, fly-away or bouncing of a body, and viscous effects including especially the interplay between viscous and inviscid contributions. The main findings are concerned with physical and mechanical insights into impact times, lift-off criteria, the borders between impact and fly-away, the principal parameters and their ranges and the influences from body shape and mass.