This paper presents a simple but complete model of the interaction of radiative flux with convective transport in an absorbing, emitting, and scattering falling film. The method also accounts for the spectral and angular variations of the radiative emissions, reflections, refractions, scattering, and of the radiative properties and intensities. Such a model is required to design Direct Absorption Solar Receivers and to numerically evaluate their performance. Previous analyses in the literature have either neglected the flow field or have not considered scattering in the film and have assumed the properties to be spectrally constant. The present model has no such drawbacks, and is easy to understand and to numerically implement on the computer. © 1990 by ASME.