Simulating high Rayleigh number natural convection in high aspect ratio horizontal rectangular enclosures using Code_Saturne platform

摘要

In the present study, buoyancy driven flows of water and air in very high aspect ratio (12-48) horizontal rectangular enclosures are studied numerically for Rayleigh numbers ranging from 10~(3)to 10~(7)using open-source CFD tools to obtain natural convection heat transfer coefficients which are then compared with established empirical correlations based on experimental results. This study has been motivated by the finding that hardly any CFD-based literature on very high aspect ratio rectangular enclosures exist and also by the fact that such enclosures have numerous applications in solar thermal systems such as solar collectors, solar passive heating/cooling systems, and solar stills, etc. It has been reported in the literature that at high aspect ratios, the numerical solution suffers from convergence issues. In the present study, using Code_Saturne as flow solver, the convergence issues have not risen and the error between numerical and experimental results increases with an increase in Rayleigh number bounded by maximum relative error of approximately 8%.