Structure of the natural convective flow above to the horizontal surface with localized heating

Pure thermal plumes have been the subject of study for the past decades. The active development of experimental and numerical research methods allowed to identify the flow characteristics in the entire region of the plume formation. Nevertheless, the bifurcation discovered in the last ten years remains to be studied, in the authors' opinion, poorly. Until now, there is no general conception of the existence of several stable flow regimes and the key features of the unsteady regime. In this paper results of an experimental and numerical study of pure thermal plume structure in the near-hot-wall region at moderate Grashof numbers are presented. Experimental data on the general flow structure and temperature field are supplemented by the results of numerical simulation. The analysis of changes in instantaneous and average values is carried out, in particular, the geometric characteristics of the near-wall layer are determined. Additionally, data on the characteristics of heat transfer, information on which in modern studies is usually limited and is fragmentary, are presented. (C) 2020 Elsevier Ltd. All rights reserved.