Convectons and secondary snaking in three-dimensional natural doubly diffusive convection

Natural doubly diffusive convection in a three-dimensional vertical enclosure with square cross-section in the horizontal is studied. Convection is driven by imposed temperature and concentration differences between two opposite vertical walls. These are chosen such that a pure conduction state exists. No-flux boundary conditions are imposed on the remaining four walls, with no-slip boundary conditions on all six walls. Numerical continuation is used to compute branches of spatially localized convection. Such states are referred to as convectons. Two branches of three-dimensional convectons with full symmetry bifurcate simultaneously from the conduction state and undergo homoclinic snaking. Secondary bifurcations on the primary snaking branches generate secondary snaking branches of convectons with reduced symmetry. The results are complemented with direct numerical simulations of the three-dimensional equations.