Convection Cells Experiment

The regular hexagonal pattern of convection cells is created when a thin sheet of viscous oil is heated uniformly from below. A small amount of aluminium is added to the oil to reveal the pattern of convection, an experiment first conducted by Henri Bénard, a French physicist, in 1900.

The convection cell phenomenon is only visible when you add mark-particles. The following experiments were filmed with a blue filter on the camera so that the aluminium particles become clearly visible.

My videos below demonstrate the nonlinear self-organisation of the convection cells a few seconds after stirring.

The movement is the upwelling of warmer liquid from the heated bottom layer. This upwelling spontaneously organises into a regular pattern of cells on low heat.

As the temperature increases, the cells’ pattern becomes more irregular and the speed of the moving particles increases as shown in the videos:

In order to follow the trajectories of the mark-particles I took long exposure photos shown below:

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