Free surface measurement of a fluid in contact with a rotating cylinder

Abstract

In this study, we present our work in which we seek to measure the relief of a liquid film driven by the rotation of a roller. This object of study presents both theoretical and practical interest. Indeed, this coating flow approaches the Landau-Levich-Deryaguin theory (Newtonian fluid film driven by a flat plate)1 . This free surface measurement also presents real scientific and technical constraints that conditions the measurement method to be used. While the fineness of the fluid film thickness at low rotation speed requires precise measurement, the dynamics of the free surface at high rotation speed requires fast measurement and the use of a minimal number of images for estimation. Several methods have been developed and applied on an opaque fluid using the principles of fringe projection profilometry. A shadowgraphy method was employed to validate the obtained results. Although used in a specific case, the method employed has potential for various applications where a free surface measurement is required.