Two-dimensional numerical simulation of a steady-state buoyancy-driven flow in a semi-confined enclosure with a line heat source

Abstract

A two-dimensional numerical simulation was conducted to study displacement ventilation flows inside a rectangular space with a single line heat source, with the working fluid connected to an external ambient fluid through upper and lower vents. Our preliminary aim was to benchmark our well-resolved DNS code for the prediction of steady-state flow behaviour against previously published numerical and experimental results. The steady-state height of the interface between upper buoyant and lower ambient layers and the steady-state buoyancy in the upper layer, predicted by a well-resolved DNS, were compared to experimental results and mathematical models. Our numerical results agreed reasonably well with experimental results and mathematical models, and showed a better agreement than the previous numerical results obtained using the standard k − ϵ models. In most regions, the power spectra of velocity fluctuations conformed to the -3 power law, however there were some regions where the -5/3 Kolmogorov law gave a better fit. Transition phenomena from periodic to chaotic regimes were observed with increasing Reynolds number.