Up to the unsteadiness of axisymmetric thermocapillary flows in a laterally heated liquid bridge

Axisymmetric flows of fluids of various Prandtl numbers, Pr, in a cylindrical and undeformable liquid bridge submitted to a lateral heating are studied in a zero gravity environment, up to their transitions to unsteadiness. The governing equations are solved numerically by a pseudospectral scheme. The results depend on Pr, in a nonmonotonic fashion, as, for instance, the threshold of the onset to unsteadiness. It has always been reached, except for our Pr=1 experiment, run up to a Marangoni number value Ma=10(6). The steady flows at very high Reynolds numbers (up to 10(7)) offer a rich structure. A first incursion into unsteadiness shows different flow structure evolutions, depending on whether Pr is smaller or larger than one. (C) 2000 American Institute of Physics. [S1070- 6631(00)01801-8].