Unsteady flow over a rotating and vertically moving disk with variable fluid properties

A numerical solution is worked out for unsteady flow around a revolving disk exhibiting upward/downward motion. A temperature-dependent viscosity model is introduced that yields a system in which momentum and energy equations are coupled in terms of a parameter theta(e). The disk revolves with the time-dependent angular velocity Omega(t) and vertically moves with the axial velocity (a) over dot (t), where a(t) denotes the location of disk at any time t. The considered expressions of a(t) and Omega(t) suggest that upward/downward motion of the rotating disk leads to the case of accelerated/decelerated disk. Solutions are worked out by a widely employed routine bvp4c of MATLAB. The vertical motion of the disk leads to a two-dimensional flow problem when the disk is nonrotating. However, simultaneous vertical movement and rotation of the disk impart a three-dimensional motion. A marked variation in solution profiles is detected whenever temperature dependency in fluid viscosity is retained. In addition, the deceleration phenomenon of the disk declines heat transfer rate from the surface.