Blade coating process using hyperbolic tangent model: a perturbation method

Abstract Blade coating is a technique where the fluid is applied to a surface using a fixed blade, providing economic advantages compared to other coating technologies. It is widely used in producing paper, preserving information, manufacturing photographic films and magnetic storage devices. This article examines the blade coating process using hyperbolic tangent model. With the help of mass and momentum conservation laws, the mathematical equations are obtained and then simplified using lubrication approximation theory (LAT). A well-known perturbation method is used to solve the resulting equation. The graphical results are produced for various values of blade height ratio ( k ) and Weissenberg number ( We ) on velocity, pressure and pressure gradient while the blade load is given in tabulated form. It is observed that both parameters k and We are responsible to increase velocity in plane and exponential coaters. It is also interesting to note that hyperbolic tangent model ( We = 0.8) predicts 26.92 % lower pressure in comparison to Newtonian model at ( x = 0.6706) in plane coater. Further, by increasing the value of k and We , the blade load declines in plane and exponential coaters.