Natural convection cooling of rectangular and cylindrical containers

Scalings are obtained for the development of unsteady natural convection, both in rectangular and vertical circular containers, and are validated by comparison with results obtained using direct numerical simulation. It is found that the numerical results agree well with the scalings. Three main stages of flow evolution are identified and the differences at each of these stages between the rectangular and cylindrical geometries are quantified. It is shown that in the flow regimes considered there is a difference in thermal boundary layer thickness; that the horizontal intrusion layer has a uniform thickness for the rectangular flow, but increases towards the symmetry axis for the cylindrical flow; and that the rate of stratification is much faster for the cylindrical geometry. (C) 2001 Elsevier Science Inc. All rights reserved.