Experimental and numerical study of convective flow structure above heated horizontal plates of different sizes

Abstract

Free thermal convection above heated plates formed in circles of different diameters is studied within our paper. Experimental and numerical studies are carried out in a three-dimensional tank filled with water under specified boundary conditions. The initial stage of thermal convection development is mainly considered. The study of liquid flow structure is particularly observed, as well as evolution of temperature field in a plane of the central section of the working sections. Within the study different heating conditions are considered: the diameter of the round source is in the range from 0.010 to 0.024 m, and the Rayleigh number varies in the range from 1.0·102 to 1.30·105. The standard system of Navier-Stokes equations is numerically solved by finite element method to study systematically convection from heat sources of various sizes by the software package COMSOL Multiphysics. Values of the control parameter are estimated in the course of the work. At the control parameter the transition from one flow regime to another one is observed. In addition, an experimental study is carried out to verify the results of numerical simulation. As a result, a qualitative agreement has been obtained between the calculated and observed flow structures during the experiments.