Effect of Solar Radiation on Thermal and Hydrodynamic Conditions in Laminar, Open Channel Flow

Abstract

A three-dimensional laminar flow model has been used with a one-dimensional radiation transfer model to predict the response of a slowly moving liquid layer to solar irradiation. Calculations performed for a range of liquid velocities, liquid and substrate radiative properties, and solar irradiation reveal the important influence of buoyancy forces on hydrodynamic and thermal conditions. Buoyancy forces induce a secondary flow which takes the form of longitudinal vortices and/or ascending-descending thermals. Onset of the secondary flow may be advanced and the strength of the flow may be enhanced by increasing the irradiation and the albedo or by decreasing the extinction coefficient, substrate reflectivity, and velocity.