The flow past a circular cylinder in a rotating frame is examined when the Rossby number Ro is O(E½), where E is the Ekman number. Previous studies of the configuration have shown that, provided the ratio Ro/E½ is less than a certain critical value, the flow around the cylinder is determined by the classical potential-flow solution. However, once Ro/E½ is greater than that critical value the E1/4 layer on the surface of the cylinder, which is rather like a boundary layer in a high-Reynolds-number non-rotating fluid, can separate from the cylinder and distort the potential flow. In this study the form of the flow once separation has occurred is examined using a method analogous to the Kirchhoff free-streamline theory in a non-rotating fluid. The results are compared with published experimental and numerical data on the flow for various values of Ro/E½.

The flow past a cylinder in a rapidly rotating frame is described when the Rossby number Ro is O(E½), where E is the Ekman number. Previous studies of the configuration have noticed the development of a singularity within the E¼ layer at the rear stagnation point once the ratio Ro/E½ is larger than a critical value, and concluded that the boundary-layer flow is unsteady. In this paper a description of a steady boundary-layer flow for this parameter range is presented, showing the development of flow separation as Ro/E½ approaches a larger critical value. Details of the flow once the E½ layer has separated from the cylinder are also described.

showed that a temperature flux condition on a sloping non-slip surface in a stratified fluid can generate a slow steady upward flow along a thin 'buoyancy layer'. Their analysis is extended here to the more-general case of steady flow in a contained fluid where buoyancy layers may expel or entrain fluid from their outer edge. A compatibility condition that relates the mass flux and temperature gradient along that edge is derived, and this allows the fluid recirculation and temperature perturbation to be determined in the broader-scale 'outer flow' region. The analysis applies when the Wunsch-Phillips parameter R is small, in the linear case for which the density variations are dominated by a constant vertical gradient.

An imposed normal temperature gradient on a sloping surface in a viscous stratified fluid can generate a slow steady flow along a thin 'buoyancy layer' against that surface, and in a contained fluid the associated mass flux leads to a broader-scale 'outer flow'. Previous analysis for small values of the Wunsch-Phillips parameter R is extended to the nonlinear case in a contained fluid, when the imposed temperature gradient is comparable with the background temperature gradient. As for the linear case, a compatibility condition relates the buoyancy-layer mass flux along each sloping boundary to the outer-flow temperature gradient. This condition allows the leadingorder flow to be determined throughout the container for a variety of configurations.

Low-Rossby-number flow past a circular cylinder in a rapidly rotating frame is studied when 1 < N < 2, where N is equal to E½/Ro in terms of the Ekman number E and Rossby number Ro. For this parameter range the E¼ boundary layer contains a singularity at the rear stagantion point. The asymptotic structure of this singularity is shown to consist of three distinct asymptotic regions, one of which is viscous while the others are inviscid. New accurate numerical solutions of the boundary-layer equation confirm this singularity structure. The use of Von Mises coordinates both simplifies the analysis, and enables numerical solutions to be found closer to the critical value N = 1, beneath which the flow separates upstream of the rear stagnation point.