An exhaustive bifurcation diagram of the steady and initially stable periodic solutions arising in double-diffusive convection of an Ar–CO2 mixture confined in a vertical slot is numerically unfolded in the balanced buoyancy case, with the particularity of taking into account the Soret effect. The consequences of modifying the linear problem including a new term to the equations are first examined. Next, a complex bifurcation diagram of equilibria and periodic orbits is shown. It includes a great amount of extended and localized patterns of convection, retaining or not the initial center symmetry. The stability of the branches of solutions with respect to arbitrary perturbations is analyzed. The study shows that the stable steady flows maximize the mass and heat transport. Two types of stable periodic oscillations have been found coexisting at low Rayleigh number; those attached to the lids, bifurcating from patterns of top and bottom localized vortices, and those bifurcating from patterns of extended vortices. The analysis of the kinetic energy equation at selected bifurcation points out that the power supplied by the temperature and solutal buoyancy terms are the most important, and that they remain always almost in balance.
Umbría et al. (Mon,) studied this question.