Discrete ordinates thermal radiation with mixed convection to involve nanoparticles absorption, scattering and dispersion along radiation beams through the nanofluid

This paper studied a two dimensional fluid flow and heat transfer in a finned open cavity filled by a water/Al2O3 nanofluid. Discrete ordinates (DO) method was used to investigate the effects of nanoparticle absorption and dispersion coefficients on the volumetric radiation rays passing a nanofluid. The employed nanofluid was water (base fluid) and alumina nanoparticles. A relatively, low volume fraction of the nanoparticles was needed for the preparation of the semitransparent medium. The finite volume technique of SIMPLE algorithm was coupled to DO to solve the continuous, momentum, and energy equations. The enclosure inner walls are the gray diffuse emitters and reflectors. As a result, a new dimensionless energy equation was presented in which could involve both effects of mixed convection and thermal radiation of DO based on Reynolds, Prandtl and Planck numbers. The results of the present study are different from previous studies, which neglected the effects of radiation or even considered them with inappropriate radiation method of Rosseland’s approximation for the nanofluid medium.