I suggest that you consider the sites and papers by Graham de Vahl Davis, Patrick Le Quéré, Pierre Haldewang, Gilbert Accary, Richard Rasquetti, Robert Sani, Franz Rosenberger, Jean-Pierre Fontaine, Bernard Zappoli, Georg Müller, Victoria, Timchenko, John Reizes, Eddy Leonardi, Brian Launder, Roger Peyret, aso ... you can get files in my own site in Research Gate that dealt with natural convection, heat transfer, instabilities, solidification, supercritical fluids, ... for many years and available to be read on sites.
You can find hystorical references for the 2D steady laminar case here: https://www.researchgate.net/publication/245324056_Multidimensional_single-step_vector_upwind_schemes_for_highly_convective_transport_problems
If you are interested in turbulent natural convection, more recent papers are available
Article Multidimensional single-step vector upwind schemes for highl...