Competition between Different Symmetries in Convective Patterns

Abstract
The transition between hexagons and rolls in convective patterns has been studied in pure water under non-Boussinesq conditions. The transition is characterized qualitatively by shadowgraph images and quantitatively by heat-flow measurements and a local technique based on the deflections of a laser beam. We also show that with this local technique one can recover global quantities such as the convective heat flow.