EXCITATION OF SPIRALS AND CHIRAL-SYMMETRY BREAKING IN RAYLEIGH-BENARDCONVECTION

Spiral-defect populations in low-Prandtl number Rayleigh-Benard convec tion with slow rotation about a vertical axis were measured in carbon dioxide at high pressure. The results indicate that spirals act like ' 'thermally excited'' defects and that the winding direction of a spira l is analogous to a magnetic spin. Rotation about a vertical axis, the spiral analog of the magnetic field, breaks the zero-rotation chiral symmetry between clockwise and counterclockwise spiral defects. Many p roperties of spiral-defect statistics are well described by an effecti ve statistical-mechanical model.