Title: Levitation and Locomotion on an Air-table of Plates with Herringbone Grooves

Speaker: John Hinch, U. Cambridge

Abstract: Experiments in ESPCI in Paris and numerical simulations in Darmstadt have shown that plates with herringbone grooves in their base are accelerated on a smooth air-table in the direction that the chevron grooves point, while smooth plates on an air-table with herringbone grooves are accelerated in the opposite direction. Newton's third law? Not quite. Hinch will discuss a simple two-dimensional model that is constructed of the air flow down a long channel with pressure-controlled influx across the lower boundary: lubrication theory with inertia or boundary layers without an outer flow. Limiting cases are considered of low and high Reynolds numbers, and of small and large pressure drop down the channel compared with the pressure drop across the porous plate; all tested against numerical solutions. The levitation and locomotion forces are calculated, with a relatively simple prediction for the locomotive acceleration; which fits the experimental data with plausible excuses.

Special Note: This talk is part of the The Inaugural Stephen H. Davis Symposium

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