INSTABILITIES OF A LIQUID LAYER LOCALLY HEATED ON ITS FREE-SURFACE

We report experimental results concerning patterns in a model experime nt built to study buoyant-thermocapillary-driven flows. The fluid is s ituated in a cooled cylindrical container and locally heated on its fr ee surface. The resulting temperature gradient induces a basic flow wh ich draws the surface fluid from the hot center toward the cold bounda ry. When the gradient is increased and depending on the height of liqu id, the basic flow destabilizes into different stationary patterns. Ab ove a second threshold, the patterns become time-dependent. These diff erent instabilities are characterized and compared to recent theoretic al results. (C) 1997 American Institute of Physics.