Lunar exploration for water deposits by electrical methods

Lunar exploration for water deposits by electrical method

Transition from Ekman flow to Taylor vortex flow in superfluid helium

By numerically computing the steady axisymmetric flow of helium II confined inside a finite aspect ratio Couette annulus, we determine the transition from Ekman flow to Taylor vortex flow as a function of temperature and aspect ratio.We find that the low-Reynolds number flow is quite different to that of a classical fluid, particularly at lower temperatures.At high aspect ratio our results confirm the existing linear stability theory of the onset of Taylor vortices, which assumes infinitely long cylinders.Comment: 12 pages, 8 figures; submitte

A novel drifter designed for use with a mounted Acoustic Doppler Current Profiler in shallow environments

We present a novel design for a surface drifter, mounted with a pulse-coherent Acoustic Doppler Current Profiler (ADCP) for measuring near-surface (depths 0.18-1 m) flows. During repeated drifter deployments over the tidal flats of Skagit Bay, the mounted ADCP recorded high quality and high resolution profiles of velocity in depths as shallow as 0.4 m. Depth-dependent velocities revealed regions of vertically sheared currents and wave motions not resolved by surface drifters alone. Although the cost of ADCPs is substantial, the drifter bodies were low cost, robust, and of simple construction