Effect of Triangular Corrugations on Dynamic Characteristics of Film Flow

Abstract

Thick film flow in a narrow channel is investigated by simulations and experiments. The influence of obstacle and corrugations on liquid film flow is studied in simulations. LIF (light induced fluorescence) method is applied to visualize the flow field close to the substrate in the experiments. With the validated 3-D simulations, numerical investigation of film flow over triangular corrugations can be done. The results indicate that eddies in the trough of corrugations are generated in two ways. Eddies generated in the first way are mainly induced by the geometry of the substrate with strong undulated corrugations. On corrugations with a small steepness, eddies generated in the second way are primarily induced by inertia force and their formulation are depended on Reynolds number. Whenever corrugations are steep or smooth, eddies in the troughs always have two variation periods with regard to Reynolds number. In the first period, the eddy size enlarges dramatically with increasing Reynolds number. In the second period, increasing Reynolds number has little influence on the eddy transformation. A smooth corrugation will delay the transition point of the two periods, and reduce the difference between them. Film flow over arbitrary geometric corrugations is simulated and the stagnant point movement is investigated. Similarity theory in fluid dynamics is verified, which proves that results of this study with relatively large scale model provides basic knowledge that can be used to predict flow behavior in small scale corrugated plates in industry.