It is fascinating to think that the ideas of two 19th century naval architects could offer useful insights for 21st century scientists contemplating the exploration of our planetary system or monitoring the long-term effects of a neurosurgical procedure on gait. The Froude number, defined as Fr = v2/gL, where v is velocity, g is gravitational acceleration and L is a characteristic linear dimens...

The problem of a plane bubble rising in a 2-D tube is revisited using Birkhoff’s (1957) formulation. The equations in this formulation have a one parameter (Froude number F ) family of solutions which are divided into three regimes characterized by distinct topologies at the apex. These equations are solved numerically using a conventional series representation method and Newton’s iterations. T...

A new approach to simulating spherical shallow-water flows is described and illustrated. The approach exploits the distinction between slow vortical motions and fast gravity waves at leading order. Contour advection is used for the vortical part, specifically for the potential vorticity. This allows an accurate representation of the vortical dynamics at modest grid resolution. New variables are...

The baroclinic tidal regime of the fjord Loch Etive (Scotland) is studied. Analysis is performed on the basis of both in situ data and numerical simulations, with the use of a fully nonlinear nonhydrostatic fine-resolution model. It was found that the crest of the sill that separates Loch Etive into inner and outer parts is subjected to a supercritical flow regime with maximum Froude numbers in...

Vortex formation from a horizontal cylinder coincident with a free surface of a shallow water flow having a depth of 25.4 mm was experimentally investigated using the particle image velocimetry technique. Instantaneous and time-averaged flow patterns in the wake region of the cylinder were examined for three different cylinder diameter values under the fully developed turbulent boundary layer c...

The spatio-temporal scaling relationship for individual channels in braided streams is shown to be identical to the spatiotemporal scaling associated with constant Froude number, e.g. FrZ1. A means to derive this relationship is developed from a new theory of sediment transport. The mechanism by which the FrZ1 condition apparently governs the scaling seems to derive from the sensitivity of sedi...

For centuries, elephant locomotion has been a contentious and confusing challenge for locomotion scientists to understand, not only because of technical difficulties but also because elephant locomotion is in some ways atypical of more familiar quadrupedal gaits. We analyzed the locomotor kinematics of over 2400 strides from 14 African and 48 Asian elephant individuals (body mass 116-4632 kg) f...