THE STABILITY OF THE STOKES LAYER IN PERIODIC ORBITAL FLOW AROUND A CIRCULAR-CYLINDER

In this paper we carry out a linear stability analysis within the Stok es layer that, under suitable conditions, forms at the surface of a ci rcular cylinder in periodic orbital motion. The analysis is related to that performed by Seminara [1, 2] in the Stokes layer on a torsionall y oscillating cylinder and by Hall [3] in the Stokes layer at the surf ace of a cylinder in purely oscillatory motion. In ail cases we find t hat the minimum critical Taylor number is located where the flow at th e edge of the Stokes layer has maximum speed in each period of the mot ion.