INSTABILITY IN TAYLOR-COUETTE FLOW WITH A NON-NEWTONIAN SHEAR-THINNING FLUID

The effects of rheological parameters and geometrical configurations on the stability of non-Newtonian Taylor-Couette flows with shear-thinning behaviors are studied numerically by finite element method. These instabilities appear as toroidal vortices in axisymmetric manner, named Taylor vortices. These vortices have significant effects on hydrodynamic and heat transfer characteristics of flow. Therefore, prediction of beginning of these instabilities is important. The onset of the instability is found by studying the growth rate of the ratio of the axial velocity components to azimuthal velocity components. By introducing a modified Taylor number, the effect of rheological parameters is removed from Taylor number. So, with good accuracy, critical Taylor number for Newtonian fluid can be used to estimate the beginning of instability for non-Newtonian fluid. Our results show good agreement with pervious works.