Influence of temperature and concentration boundary layers at separation on heat and mass transfer in separated flows

The local mass transfer in separated regions is determined by means of a model for a backward-facing step in a flat plate boundary layer, where the boundary layer at separation is both laminar and turbulent, and the flow upstream of this point has an inert and active starting length. A concentration boundary layer may therefore be either present or absent. Three local separated region types are noted for laminar as well as turbulent flow boundary layers at separation, yielding a mass transfer maximum that can differ considerably from the reattachment of the flow. The Nusselt power law fuction characteristic exponents given for each flow type indicate that these exponents depend on the Schmidt or Prandtl number, so that no universal exponents exist for the Reynolds number in separated flows.