On the Use of Rotating Hydraulic Models

Abstract

Two problems regarding the use of rotating hydraulic channel flow models are addressed. The first concerns the difficulties encountered when trying to identify the ?potential? depth for a flow of uniform (but nonzero) potential vorticity in a practical situation. Guidelines are given to cheek whether a chosen value of the potential depth is consistent with the rotating hydraulic theory. The second problem deals with the applicability of the so-called zero potential vorticity approximation. It is shown that the accuracy of this approximation depends on the ratio of the channel width to the Rossby radius of deformation (based on the potential depth) and the ratio of the fluid depth to the potential depth. To establish when this simplified model yields an accurate approximation of a flow of constant (but nonzero) potential vorticity, the two models are compared for a variety of channel geometries.