TAYLOR-COUETTE STABILITY ANALYSIS FOR A DOI-EDWARDS FLUID.

The stability of Taylor-Couette flow of entangled polymeric solutions to small axisymmetric stationary disturbances is analyzed using the Dol-Edwards constitutive equation in the small gap limit. A previous analysis of Karisson, Sokolov, and Tanner for the general K-BKZ equation, of which the Dol- Edwards equation is a special case, reduces the problem to one of numerically evaluating seven viscoelastic functions of the shear rate gamma in the gap. Of these seven, only three - two of which are related to the second normal stress difference, and one of them to shear thinning - significantly affect the flow stability. The negative second normal stress difference of the Dol-Edwards fluid stabilizes the flow at low values of the Weissenberg number lambda sub 1 gamma, while shear thinning produces strong destabilization at moderate Weissenberg number.