A fundamental study of combined free and forced convective heat transfer from a vertical plate followed by a backward step

Combined forced and free laminar convective heat transfer on a vertical plate with a backward‐facing step has been studied numerically and experimentally, considering the effects of the interaction between the buoyancy and inertia forces which play a significant role in this phenomenon with the step‐geometry factor of d/L. The convective heat transfer behavior in connection with the reattachment and recirculation flows appearing in the step region has been investigated based on the numerical calculations and Mach‐Zehnder interferometer measurement under the wide range of the thermal condition. The behaviors of local Nusselt number Nu_L, velocity and temperature boundary layers and streamline fields in the recirculating region have been discussed for the various parameters of Grashof number Gr_L, Reynolds number Re_L and the geometry factor d/L. The characteristic behavior of this convection heat transfer, including the vortex flow mode in the recirculating region and the unstable fluctuating mode near the reattaching point appearing at the specific condition, has been clarified numerically and experimentally by introducing the generalized coupling parameter Gr_L/Re_L² and geometry factor d/L.