THE APPLICATION OF PARTICLE TRACKING VELOCIMETRY AND FLOW VISUALIZATION TO CURTAIN COATING

Flow visualisation and particle tracking velocimetry are both commonly used methods for investigating fluid flows. In recent years, both techniques have been applied to various two- and three-dimensional systems and have employed various levels of sophistication. In this paper, the experimental application of these methods to curtain coating flows will be discussed. Here we are primarily concerned with two-dimensional, laminar, steady-state flows. The region of interest is, however, freely located and bounded by two free liquid surfaces plus a substrate moving at high speed. Moreover, the thickness of the liquid curtain is typically less than 0.4 mm and the region of interest close to the wetting line less than 1 mm diameter. Example data for aqueous polyvinyl pyrolidone and aqueous gelatin is presented. The particle tracking images are analysed to obtain flow functions such as the rate of strain and vorticity.