This picture shows a flame in a 6.8% methane, 93.2% air mixture propagating from left to right in a Hele-Shaw cell. The cell dimensions in the plane of the image is 40cm x 60cm and the thickness of the cell in the out of plane direction is 1.27cm. The right end of the cell seen in this picture has pressure relief ports whereas the left, top and bottom sides of the cell are sealed. the plane of the cell is oriented horizontally and the images are taken through a transparent plate by a video camera mounted above the cell looking downwards. The image and the corresponding movie show flame wrinkling caused by a combination of thermal expansion, viscosity contrast between reactants and products, and the diffusive-thermal instability of premixed flames with low Lewis number.

Movies regarding pre-mixed gas flame propagation in Hele-Shaw cells are available at collection.