EXPERIMENTAL AND NUMERICAL TURBULENT BUOYANT FLOWS IN AN ENCLOSURE

The cooling of a hot surface by fluid motion has many applications in engineering. For these mixed convective problems, the forced component of fluid motion may be in the direction of the buoyancy vector or it may oppose the buoyancy force. In the present study, the opposing mode is used to study the interaction of inertia and buoyancy forces in a fluid. Both numerical and experimental techniques are used to study the flow in a two dimensional rectangular cavity. The inlet Reynolds number is varied between 800 and 1300 and the Grashof number based on the height of the enclosure is varied between 0 and 2.4 × 10¹⁰. The cases considered correspond to Archimedes numbers of approximately 0, 1, 10 and 20. The velocity, temperature and turbulent fields have been studied experimentally and computationally. Comparison of the experimental and computational results suggest that for inertially dominated and buoyancy dominated flows, the computational modelling is adequate. Difficulties arise in the prediction of the intermediate Archimedes number cases as the predicted flow is dominated by buoyancy while the experiments show more of a balance. Sources for this discrepancy are discussed.