In this chapter we turn our attention to processes of combined (simultaneous) heat and mass transfer that are driven by buoyancy. The density gradients that provide the driving buoyancy force are induced by the combined effects of temperature and species concentration nonuniformities present in the fluid saturated medium. The present chapter is guided by the review of Trevisan and Bejan (1990), which began by showing that the conservation statements for mass, momentum, energy, and chemical species are the equations that have been presented here in Chapters 1–3. The new feature is that beginning with Eq. (3.26) the buoyancy effect in the momentum equation is represented by two terms, one due to temperature gradients, and the other to concentration gradients.
KeywordsPorous Medium Nusselt Number Rayleigh Number Sherwood Number Critical Rayleigh Number
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