Abstract
This article presents a mathematical model and theoretical analysis of coating of a thin film of non-Newtonian polymers as they travel through a small space between two reverse-rotating rolls. The dimensionless forms of the governing equations are simplified with the help of the lubrication approximation theory (LAT). By using the perturbation technique, the analytical solutions for velocity, flow rate and pressure gradient were obtained. From an engineering point of view, some significant results such as thickness of the coated web, pressure distribution, separation points, separation force and power input were computed numerically. The effect of velocities ratio and Weissenberg number on these physical quantities is presented graphically; others are shown in tabular form. It is noted that the involved material parameters provide a mechanism to control the flow rate, pressure distribution, the thickness of coating, separation force and power input. Moreover, the separation point is shifted toward the nip region by increasing velocities ratio .
Highlights
Roll coating is an engineering procedure in which a uniform thin liquid film is deposited onto a substrate
Hf υ = Hr, separation force F and power input pw transmitted to the roll are presented in Tables 1 and 2 for several values of velocities ratio k and Weissenberg number We
Theoretical assessment of reverse roll-coating with the principle of Innecessary this paper,towe present
Summary
Roll coating is an engineering procedure in which a uniform thin liquid film is deposited onto a substrate. Jang et al [6] used the finite-volume method and volume of fluid (VoF)-free surface technique to 3D model of non-Newtonian flow in reverse roll-coating. Zahid et al [16] gave numerical results for second-grade materials by utilizing the lubrication approximation theory Engineering parameters such as the thickness of the coating, pressure distribution, split location, strength, roll power consumption, stresses and adiabatic temperature rise was achieved among coating roll and coated web. They presented physical parameters of engineering interest such as stresses, force, separation position, pressure distribution, power input, temperature to rolls and thickness of the coating of the web. We provide a theoretical analysis for the reverse roll-coating process of Williamson fluid films, which is drawn through a small gap between two rolls rotating in opposite directions.
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