On the validity of the Boussinesq approximation in a tall differentially heated cavity with water

Abstract

In the present work, the fluid flow and heat transfer inside an integrated solar collector installed on an advanced fac¸ade are investigated. According to Gray and Giorgini [1], the use of the Boussinesq approximation can be considered valid for variations of thermosphysical properties up to 10 % with respect to the mean value. In the configuration under study, there is a variation of about 20 % in the dynamic viscosity and 15 % in the thermal expansion coefficient. Thus, the main objective of this work is to analyse the validity of the Boussinesq approximation for the turbulent natural convection flow of water in a rectangular parallelepiped tank. The significance of the Boussinesq effects is studied comparatively by means of detailed DNS simulations.