Dimensionless heat-mass transfer coefficients for forced convection around a sphere: a general low Reynolds number correlation (Q759595)

The average Nusselt number (Nu) for mass-heat transfer from a sphere is obtained as a function of the Péclet number (P) with the dimensionless Stokes drag \(F_ 0(2/3\leq F_ 0<1)\) as a parameter. The derivation considers in detail the high Péclet number range, where the Friedlander approximation might be employed. Considering a well-known Nu-P relation for bubbles \((F_ 0=2/3)\) as the \(F_ 0=2/3\) limit of a general \(Nu=Nu(P,F_ 0)\) correlation allows us to explicitly obtain a rather simple expression of that relation for arbitrary \(F_ 0(2/3\leq F_ 0<1)\). The maximum error involved in using such a simple formula is estimated to be 6\%.