Low-Reynolds boundary driven cavity flows in a thin liquid shell

Low-Reynolds recirculating cavity flows are traditionally generated from lid-driven boundary motion at a solid-fluid interface or result from shear flow over an opening. Such flows are typically described by the equations of creeping motion, where viscous forces are dominant. We illustrate using Particle Image Velocimetry (PIV) an original family of boundary-driven cavity flows occurring, in contrast to classic configurations, at a liquid-gas interface: thermally-induced Marangoni flows in a thin liquid shell generate forced, steady-state recirculating flows inside the cavity. Forcing relies on viscous mechanisms at the boundary but resulting flow patterns are, however, inviscid. Here, the inviscid equations of fluid motion are not used as an approximation, but rather come as a result from the solution of the creeping motion equations in the region inside the sphere. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)