Numerical assessment of thin layer coating of non-Newtonian fluid during blade coating process with MHD effects

PurposeThe coating process increases the durability, quality and effectiveness of the web, is used in manufacturing of wallpapers, adhesive tapes, wrapping, protection of fabrics and metals, X-ray and photographic films, beautification, books and magazines, film foils, magnetic records, coated paper, etc.Design/methodology/approachThis paper gives a detailed study of the Oldroyd-4 constant fluid rheology during blade coating technique to check the sensitivity of velocity slippage on blade surface and magnetohydrodynamics (MHD) on final coating thickness and other mechanical properties. Heat transfer effects are also considered with viscous dissipation. The governing expressions under Lubrication Approximation Theory (LAT) are shortened and non-dimensionalized. A numerical technique with root finding algorithm is employed to determine the velocity profile, pressure and pressure gradient, shear stress, coating thickness, blade load and temperature profile. Figures and tables are exploited to show and discuss the effects of Hartmann number, slip parameter, geometrical parameter and viscoelastic fluid parameters on the flow and mechanical quantities. Comparison is also presented with previous literature under specific conditions.FindingsFrom a technical vantage point, blade load and pressure are significant results of research as they lead to varying coating thickness, which gives an efficient coating process and extends substrate life. Shear stress is directly proportional to the magnetic parameter and inversely proportional to velocity slippage on blade surface. Temperature curve increases with increment in magnetic parameter and Brinkman number, while decrease in temperature is detected from slip parameter.Originality/valueIn literature, this investigation fills a gap in the numerical prediction of slip and MHD effects on the thin layer coating of rheological viscoelastic fluid during blade coating phenomena.