The computation of buoyant flows in differentially heated inclined cavities

The paper describes the application of several RANS modelling schemes to compute natural convection flows in 2-dimensional tall rectangular cavities with differentially heated long walls and inclined at non-vertical angles. Two different wall-function modelling strategies are tested, as are the effects of employing k-" or stress transport models in the outer flow region.With the cavity inclined at 60-deg to the horizontal, with the upper side heated, the mean field is similar to that found in the vertical case, and most of the models tested perform reasonably well over much of the domain. The stress transport schemes tend to overpredict the mixing near the end walls, although this can be improved by adopting a more complex model for the turbulent heat fluxes. There are subtle differences in the turbulence fields between the 60-deg and 90-deg cases, some of which are captured by the stress transport models. When the cavity is further inclined to an angle of 5-deg, again under stable heating, the turbulence levels are quite low and, as a result, most of the models predict fairly similar mean flow profiles, in reasonable agreement with available LES data. In the final case considered, the cavity is inclined at 15-deg to the horizontal, with the lower side heated. Agreement with measurements is rather poor in this unstable case, and this is believed to be partly due to the fact that the experimentalists report large 3-dimensional roll structures in the flow, which cannot be captured by the present 2-dimensional computations.