Combined thermocapillary–buoyancy convection in a thin rectangular geometry is investigated experimentally, with an emphasis on the generation of hydrothermal-wave instabilities. For sufficiently thin layers, pure hydrothermal waves are observed, and are found to be oblique as predicted by a previous linear-stability analysis (Smith & Davis 1983). For thicker layers, both a steady multicell state and an oscillatory state are found to exist, but the latter is not in the form of a pure hydrothermal wave.

Hydrothermal-wave instabilities in thermocapillary convection are known to produce undesirable effects when they occur during the float-zone crystal-growth process, and perhaps in other situations. Suppression of the hydrothermal-wave instability produced in the model system of Part 1 (Riley & Neitzel 1998) is demonstrated through the sensing of free-surface temperature perturbations and the periodic addition of heat at the free surface along lines parallel to the crests of the hydrothermal waves.

No abstract

No abstract