LAUSR

Abstract Natural convection on a heated and polluted strip within a partial enclosure is investigated, where the baffle is attached to the right wall. Numerical solutions demonstrate that the baffle in the partial enclosure could enhance heat and mass transfer rates only when Ra (thermal Rayleigh number) is higher than the critical value and its dimensionless vertical deviation between the baffle and horizontal x -axis, represented by E , lies between −0.8 and −0.5. When Ra  ≥ 10 5 and E  = −0.50 are imposed, heat and mass transfer rates for the dimensionless length of the baffle L  = 0.8 are higher than those of L  = 0.2 and L  = 0.5; whereas, for Ra ≥8.0 × 10 5 and E  = −0.8, convective transfer rates of L  = 0.5 and L  = 0.8 are higher than those of L  = 0.2. These trends could be reversed when the regime of low Ra is established. Steady transition flows are observed as Ra varies from 1.25 × 10 5 towards 1.30 × 10 5 , where L  = 0.2 and E  = −0.6 are maintained; As Ra turns up to 8.00 × 10 5 from 7.90 × 10 5 , Nu and Sh could be enhanced sharply for L  = 0.8 and E  = −0.7. Moreover, huge divergences are observed for temperature and concentration distributions along the central axis when the steady transition flow appears in the enclosure. Present work could be significant for natural convection optimization and passive control of heat and pollutant removals from the building enclosures or electronic boxes.