Heat transfer in an absorbing and emitting nongray Boussinesq fluid within the annular gap of two infinitely long isothermal horizontal concentric cylinders is studied analytically. The Milne-Eddington approximation is employed in expressing the two-dimensional radiative transfer to include radial and tangential radiation. Results indicate that decreasing Planck number, increasing the degree of nongrayness of the fluid or increasing optical thickness increases the total heat transfer and reduces the induced buoyant flow intensity and velocities. Decreasing boundary emissivity produces the opposite effect. Because radiation decreases a fluid’s effective Prandtl number, increasing radiation causes adownward movement of the centre of the eddy formed with medium Prandtl number fluids like air.
International Journal of Heat and Mass Transfer 05/1986; 29(5-29):659-671. DOI:10.1016/0017-9310(86)90118-3