Visualization of low Reynolds boundary-driven cavity flows in thin liquid shells
Classic examples of low-Reynolds recirculating cavity flows are typically generated from lid-driven boundary motion at a solidfluid interface, or alternatively may result from shear flow over cavity openings. Here, we are interested in an original family of boundary-driven cavity flows occurring, in contrast to classic setups, at fluidfluid interfaces. Particle image velocimetry (PIV) is used to investigate the structure of internal convective flows observed in thin liquid shells. Under the specific configuration investigated, the soap bubbles liquid shell is in fact in motion and exhibits sporadic local bursts. These bursts induce transient flow motion within the cavity of order Re ? O(1). The combination of PIV and proper orthogonal decomposition (POD) is used to extract dominant flow structures present within bubble cavities. Next, we show that thermally induced Marangoni flows in the liquid shell can lead to forced, (quasi) steady-state, internal recirculating flows. The present findings illustrate a novel example of low-Reynolds boundary-driven cavity flows.
cavity flow liquid shell piv pod marangoni flow low reynolds number