Analyzing the Impact of Temperature‐Dependent Viscosity on Three‐Dimensional Flow and Thermal Fields Over a Decelerating Rotating Porous Disk

ABSTRACT This study investigates the three‐dimensional viscous flow induced by a decelerating, rotating, and vertically translating porous disk with viscosity dependent on temperature. Unlike conventional analyses that assume constant viscosity, three distinct viscosity models—constant, inverse temperature‐dependent, and exponential temperature‐dependent are systematically examined to capture realistic thermochemical behavior. The governing coupled non‐linear partial differential equations are reduced via similarity transformations and solved using a cubic B‐spline collocation scheme, ensuring higher accuracy and computational efficiency. A comprehensive parametric analysis is conducted to evaluate the impact of disk deceleration rate, angular velocity, Prandtl number, and viscosity variation parameter on the velocity and temperature fields. The results reveal that temperature‐dependent viscosity models exhibit marked deviations from constant‐viscosity predictions, particularly under elevated thermal conditions, emphasizing the importance of incorporating variable viscosity effects in high‐temperature rotating porous disk systems. The findings provide new insights into flow and heat transfer dynamics with implications for thermal engineering and advanced energy transport applications.