Heat Transfer Analysis of the Blade Coating Process Using Oldroyd 4‐Constant Nanofluid Model With Non‐Linear Slip and Magnetohydrodynamics (MHD) Effects

Blade coating is a process that applies a fluid to a surface using a fixed blade. Among various coating technologies, blade coating offers significant economic advantages. It is commonly employed in the production of paper, information preservation, the application of coloring agents, and the manufacture of photographic films and magnetic storage devices. The novelty of this work lies in the investigation of the blade coating process for an electrically conducting Oldroyd 4‐constant liquid, incorporating velocity slippage at the blade surface in an area previously underexplored. The mathematical equations are modeled with the use of Lubrication Approximation Theory (LAT) and the normalized equations of the Oldroyd 4‐constant fluid are numerically solved by the Matlab built‐in function bvp4c using Regula‐Falsi Method. The impact of sundry parameters on physical quantities is examined through graphical representation. It is noted from the theoretical results that for the fixed value of the MHD parameter ( M = 2.5 ), the coating thickness and blade load increased by 31% and 1648% respectively, for plane coater. For the exponential coater, these values increased by 29% and 1618% from their Newtonian value. These findings offer new insights into optimizing the blade coating process for complex fluid systems.