Abstract
Heat transfer measurements from a smooth and a rough (lobe structured) sphere to water (Prandtl number Pr = 7) at Reynolds numbers 3 × 103 < Re < 7.5 × 104 are described and compared to mass transfer measurements made previously under identical flow conditions but at Schmidt number Sc = 2170. The comparison shows how the molecular properties of the fluid affect the transfer of smooth and rough particles and, by inference, how the results of transfer measurements in liquids can be applied to air. The new measurements help to establish a safer basis for model experiments. They essentially confirm previously made extrapolations on the roughness effect on the convective heat and mass transfer of spherical hailstones.
