Unsteady Buoyant Convection and Liquid-Solid Phase Change in a Power Law Fluid Within a Differentially Heated Square Cavity

摘要

In the thermal processing of canned foodstuffs, a problem that frequently arises is related to the heating or cooling time required to process the contents of a can. The liquid-solid phase change phenomenon in a non-Newtonian fluid undergoing transient natural convection in a square cavity is the fundamental problem that is investigated. The unsteady Navier-Stokes equations and the convection-diffusion equation are the required mathematical formulation. Phase change effects are introduced through an apparent specific heat model. Because the fluid is initially at rest, the buoyant motion is transient, leading to a complex problem with unsteady fluid motion, temperature dependent rheology, and eventually phase change. A Finite Volume method was used to discretize the governing equations. Transient temperature and velocity fields were obtained for varied non Newtonian power index n. It was found that the motion of fluid is augmented when n increases. This power law index also influences the final shape of the solid/liquid interface.