CFD modeling and validation of turbulent natural convection in an air-filled square cavity

Computational Fluid Dynamics (CFD) is becoming an important modelling tool for studying a variety of building physics problems. In this paper, CFD is applied to calculate turbulent natural convection and the associated convective transfer coefficients in an air-filled square cavity. CFD validation is performed by comparison of the numerical results with a set of high-accuracy, high-resolution experimental data published in literature and with an existing empirical correlation for convective heat transfer along a flat vertical plate. The experimental work is one of the first studies developed for benchmarking CFD models for low turbulence natural convection and was conducted for a 0.75 m x 0.75 m x 1.5 m cavity. The numerical results are expressed in terms of the velocity and temperature distribution in the cavity, the boundary layer velocity and temperature profiles and the resulting convective heat transfer coefficients along the cavity perimeter. It is shown that with the correct combination of turbulence model, near-wall treatment and near-wall grid resolution, a close to very close agreement between the CFD simulations and the experimental data is obtained. For all turbulence models, the simulated average convective heat transfer coefficient is within 8.3% of the empirical correlation.