High resolution laboratory experiments with large aspect ratio are being conducted for thin fluid layers heated from below and bounded from above by a free surface. The fluid depths are chosen sufficiently small (0.06 cm) so that surface tension is the dominant driving mechanism; the Rayleigh number is less than 5 for the results reported here. Shadowgraph visualization reveals that the prim\ary instability leading to hexagons is slightly hysteretic (~1%). Preliminary measurements of the convection amplitude using infrared imaging are also presented.
Schatz, M.F., Van Hook, S.J., Swift, J.B., McCormick, W.D., Swinney, H.L., Onset of Hexagons in Surface-Tension-Driven Benard Convection, 2nd Microgravity Fluid Physics Conference, NASA Lewis Research Center, Cleveland, OH, CP 3276, pp. 33-38, June 21, 1994.