An experimental study of natural convection on a vertical surface with neighboring isothermal and isoflux heating

Natural convection on a vertical surface composing of isothermal and isoflux sections is widely present at envelope of buildings and in nature. The interaction between boundary layer flows adjacent to isothermal and isoflux sections of the vertical surface can result in different heat and mass transfer rates. The non-dimensional governing parameters for such a flow configuration are analyzed in this study. Shadowgraph visualization and thermistor measurement are carried out to observe the isothermal boundary layer flow (TBLF) and isoflux boundary layer flow (FBLF). In particular, the flow configurations are focused for which the FBLF and TBLF have the same and the opposing flow direction. The flow configurations are characterized under different regimes with TBLF dominance, FBLF dominance and comparable TBLF and FBLF, and the transient features are discussed. Graphic abstract