ON THE STABILITY OF NONISOTHERMAL CIRCULAR COUETTE-FLOW

The stability of a circular Couette flow with internal heat generation is studied in the region between two coaxial cylinders. The inner cyl inder is rotating with constant velocity while the outer one is kept a t rest. The investigation is carried out for wide ranges of the Prandt l number and radius ratio R, for the axisymmetric mode (n=0) and the f irst two asymmetric modes (n=1,2), respectively. For small to large ga ps (R=0.95, 0.7, 0.4), axisymmetric perturbations are the single main cause of instability. The growths of the Prandtl and Taylor numbers le ad to a decrease of the critical Grashof number. Stabilization of the Couette flow is possible for very large gaps (R=0.1), but the region o f stabilization decreases for large Prandtl numbers. The stability bou ndary is determined by the concurrence of axisymmetric (n=0) and spira l (n=1) modes in the case of very large gaps.