sheared electroconvection in a smectic film

A smectic liquid crystal forms a thin film, like a soap bubble. Here, we have such a film in an annular holder about 1 cm across. The variation in color comes from thickness variations. A voltage is applied between the inner and outer edge. At the same time, the inner electrode is rotated to produce a shear flow. The convection eventually produces 6 localized vortices (which rotate in the same sense as the inner electrode) and 6 large return flows. Movie by Peter Kruse. Video by Stephen Morris.