SURFACE-TENSION-DRIVEN BENARD CONVECTION IN SMALL CONTAINERS

The onset and the form of surface-tension-driven convection in three different small circular and one small square container has been studied experimentally. In the smallest circular container, with increasing aspect ratio, the pattern consisted of first a circular roll and then segments of a circle outlined by different numbers of azimuthal nodal lines, with up to six segments. Simple solutions in the square container were the one-cellular pattern and a pattern consisting of four square cells. Unexpected solutions formed when the number of the cells in the square container was not a square number. When the aspect ratio permitted two cells, two triangular cells were observed. With space for three cells, one square cell and two wedge-shaped cells formed. The onset of convection in all fluid layers was characterized by a steep increase of the critical Marangoni number with decreasing aspect ratio. © 1990, Cambridge University Press. All rights reserved.