Unsteady natural convection in a cavity with non-uniform absorption of radiation

A study of the unsteady natural convection in a cavity which was heated by the absorption of radiation entering through part of the surface is reported. While a general scaling analysis is quite complex, involving five separate timescales, most naturally occurring problems fall into just one regime, and it is only this regime which is discussed. To test the scaling, a series of laboratory experiments were performed in which the radiation parameters (surface flux and attenuation coefficient) were varied. The method by which these parameters were determined is also discussed. Numerical experiments were used to extend the parameter range, and the results of all these experiments confirmed the validity of the scaling over a range of parameters.