Chiral pattern in nonrotating spherical convection

When the Rayleigh number is low, Rayleigh-Benard convection in a nonrotating spherical shell with central gravity has symmetric solutions in terms of three-dimensional discrete rotation. All the known patterns with the regular polyhedral symmetries accompany reflection symmetry. We found an alternative type of steady convection in a nonrotating spherical shell by computer simulations. The pattern has the discrete rotational symmetry of a regular tetrahedron with no reflection symmetry. The convection consists of six pairs of spiral rolls placed on 12 faces of a spherical dodecahedron. Depending on the winding of the spirals, there are two possible configurations that are mirror images of one another.

Automated summary

When the Rayleigh number is low, Rayleigh-Benard convection in a nonrotating spherical shell with central gravity has symmetric solutions in terms of three-dimensional discrete rotation. We found an alternative type of steady convection in a nonrotating spherical shell by computer simulations, which has the discrete rotational symmetry of a regular tetrahedron with no reflection symmetry.