Liquid spreading and thin film flows over complex surfaces

The flow of thin viscous films over complex surfaces is relevant to the description of heat and mass transfer processes over structured packings. Experiments have been performed over a wide range of parameters to characterize the behavior of the liquid film over complex surfaces. A two dimensional streamline function is used to compute the components of the velocity field and to reduce the equations of motion to a single, nonlinear, ordinary differential equation for the film thickness. Generalized Nusselt type solutions have been obtained for flow over both the macro- and micro-structure of the ordered packing, kept with its corrugations inclined as well as horizontal.; A viscous long wave type approximation has also been used to derive a film evolution equation for both gravity and capillarity induced bulk spreading of a liquid point source over inclined flat surfaces as well as complex surfaces. This simulates the flow from a drip point over ordered packings in packed beds. It was experimentally observed that in the absence of contact lines the liquid point source retains a shape similar to a Gaussian distribution as it spreads over the solid surface.; One of the primary objectives of this work is to predict non-adjustable parameters like the interfacial area, liquid holdup, contact times and mass transfer coefficients using a more fundamental basis, than the empirical correlations that are so prevalent today. The effect of the size of the structured packing as well as liquid properties on these parameters will be explored. The methodologies to be followed in the prediction of many of the important non-adjustable parameters needed for the design of a packed column have been laid out.