Verification of the method of reconstructing convective velocity fields on the basis of temperature fields in vertical, differential and equally heated, open and closed channels

Abstract

This paper describes a method of reconstructing velocity fields, i.e. a numerical reconstruction procedure (NRP) that involves the numerical processing of experimentally measured temperature distributions in free convection heat transfer. The NRP consists in solving only the continuity and Navier–Stokes equations with an additional source term. This term is proportional to a known temperature (e.g. from a thermal imaging camera) and replaces the Fourier–Kirchhoff equation, which also means that the NRP does not require boundary conditions associated with the temperature to be formulated.In order to verify the NRP, the experimental results of two published cases were taken into consideration. In the first case, the temperature and velocity distributions were determined during free convection heat transfer in a closed cavity, i.e. in a vertical channel formed between differentially heated plates. Subsequently, the velocity distributions obtained by the NRP were compared directly with the experimental results. However, in order to verify the correctness of this method for the entire field, not just for the individual locations, free convection heat transfer measurements in an open channel formed between two isothermal, equally heated plates were considered. A thermal imaging camera was used to detect the temperature field in air. In this case, verification of the NRP method required the results obtained in the form of a reconstructed velocity field to be compared with a field obtained using standard numerical calculations (SNC).Importantly, the NRP provides new opportunities for thermal imaging cameras equipped with a mesh for air temperature detection, for example, the visualisation of air velocity fields in free convective heat transfer.