Effect of the supporting disks shape on nonlinear flow dynamics in a liquid bridge

Abstract

The stability of convective flows in a non-homogeneous temperature field is affected by the shape of the container hosting the fluid. We present a nonlinear two-phase computational study of convection in a liquid bridge that develops under the action of buoyancy and Marangoni forces. The hydrothermal instability is examined for three shapes of disks supporting liquid bridge: both disks flat, the upper (hot) disk tapered, and the lower (cold) disk tapered. Steady flow is also analyzed for the case that both disks are tapered. In all the cases of instability, the flow pattern comprises, but is not limited to, a hydrothermal wave with an azimuthal wavenumber m = 2. An intriguing flow pattern is observed in the case of flat disks when the nonlinear interaction between the modes m = 0 and m = 2 leads to quasiperiodic motion forming a torus in the phase space. The torus originates from two traveling waves (TW) with the same mode m = 2 but with distinct (close) frequencies. Note that this was not observed in the one-phase model. The case with a tapered cold disk reveals an oscillatory state with a single TW wave associated with m = 2 mode. In the case of a tapered hot disk, an axially symmetric TW with m = 0 is observed first and, at later times, is accompanied by a TW with m = 2.