A mathematical model is developed with which the reading from a piezometer ring may be predicted from the individual wall static measurements and from this the conventional form of ring is shown to be unreliable in asymmetrical flow. An alternative form of ring known as the Triple-T is analysed and shown to provide a true mean pressure in all cases. It is recommended that this form be used in all future test work. Tests demonstrating the validity of the theory are described.

An analytical–numerical analysis of the fluid motion induced by an impulsive change in the angular velocity of a rotating disk is presented. Separate solutions are derived for the early development and for the approach to the ultimate state. The superposed flow is found to have variations on two length scales, and is characterized by the generation and propagation of shear-type wave trains. These decaying wave trains ultimately lead to the new von Kármán state corresponding to the changed angular velocity of the disk.

A finite-amplitude model of baroclinic instability is studied in the case where the cross-stream scale is large compared with the Rossby deformation radius and the dissipative and advective time scales are of the same order. A theory is developed that describes the nature of the wave field as the shear supercriticality increases beyond the stability threshold of the most unstable cross-stream mode and penetrates regions of higher supercriticality. The set of possible steady nonlinear modes is found analytically. It is shown that the steady cross-stream structure of each finite-amplitude mode is a function of the supercriticality.

Integrations of initial-value problems show, in each case, that the final state realized is the state characterized by the finite-amplitude mode with the largest equilibrium amplitude. The approach to this steady state is oscillatory (nonmonotonic). Further, each steady-state mode is a well-defined mixture of linear cross-stream modes.