Abstract
We present a review of our recent experimental results on the stability and pattern selection in the Couette-Taylor (CT) flow of dilute polymer solutions. We succeeded in varying the solution elasticity by three orders of magnitude in a controlled way and have obtained a diagram of flow states in the whole elasticity range. It made it possible to study the role of elastic versus inertial effects in destabilization of the CT flow and pattern selection above the instability threshold. We investigated transformation of the flow instabilities from purely inertial to purely elastic and studied the properties of new elastic and inertio-elastic modes. By changing the rheological properties of the polymer solution, we verified the suggested criterion of elastic instability.