The convective stability of circular Couette flow induced by a linearly accelerated inner cylinder

The onset of Taylor–Görtler instability induced by a linearly accelerated inner cylinder in Couette flow is analyzed by using the propagation theory based on linear theory and momentary instability concept. It is well-known that the primary transient Couette flow is laminar but secondary motion sets in when the inner cylinder velocity exceeds a certain value. The dimensionless critical time τc to mark the onset of instability is presented here as a function of the modified Taylor number T. Available experimental data indicate that for large T secondary motion is detected starting from a certain time τ≈2τc. This means that the growth period of initiated instabilities is needed for secondary motion to be detected experimentally. It seems evident that during τc⩽τ⩽2τc secondary motion is relatively very weak and the primary diffusive momentum transfer is dominant.