Investigation of radiative heat transfer in complex geometries using blocked-off, multiblock, and embedded boundary treatments

A prediction of radiative heat transfer in a complex geometry is performed using different boundary treatments such as blocked-off, spatial-multiblock, and embedded boundary methods. The formulation of embedded boundary treatment for finite volume is derived. The finite-volume method (FVM) is used to model the radiative transfer in an absorbing and emitting medium which is maintained at an isothermal condition and enclosed by cold and black walls. While the body-fitted grid system is used for the spatial multiblock treatment, the Cartesian grid system is chosen for the others. Their results are compared and discussed for three different cases, including a trapezoidal enclosure, a semicircular enclosure with internal block, and an incinerator-shaped enclosure. The accuracy obtained by application of each treatment is shown to be highly satisfactory. Consequently, each treatment is suitable for modeling the radiative heat transfer in the complex geometry. However, the solution obtained by the blocked-off treatment yields some errors compared with the others, since the Cartesian grid used in the blocked-off treatment cannot configure exactly the complex boundaries. Especially, the radiative heat flux on the nonorthogonal wall is largely underestimated due to its stepwise description of the wall.