Unsteady analysis of natural convection in a square enclosure filled with non-Newtonian fluid containing an internal cylinder

This study investigates the laminar unsteady natural convection in a square enclosure with an internal circular cylinder containing non-Newtonian fluid. The results illustrate the effect of vertical movement of an internal circular cylinder on the flow and heat transfer mechanism within a square enclosure for Rayleigh numbers ranging from 103 to 106. The Prandtl number was fixed to 10. The internal cylinder was positioned at three different locations along the vertical center line near the isothermal bottom wall, at the center, and near the isothermal top wall. The effect of the power law index in the range of 0.6 to 1.6 with a step size of 0.2 on the natural convection is also examined with respect to other parameters. The numerical solution was unsteady symmetric for “at the center” case and unsteady asymmetric for “near the isothermal bottom wall” and “near the isothermal top wall” cases at n = 0.6 for Ra = 106.