Characteristics of a deep sea neutrally buoyant float

Aagaard, E.; Ewart, Terry E.

doi:10.1109/oceans.1973.1161265

Cited by 1 publication

(2 citation statements)

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“…The first oceanographic float (Stommel 1955;Swallow 1955) was calibrated at build to have a given buoyancy. The ability was added afterwards to adjust the buoyancy in situ, by expanding or contracting an external trim chamber (Aagaard & Ewart 1973) or an external bellows (Cairns 1975). Several generations of floats followed, described by Rossby, Dorson & Fontaine (1986), Swift & Riser (1994), D'Asaro et al (1996) and D'Asaro (2003, among others, leading to the autonomous Lagrangian floats of today.…”

Section: Introductionmentioning

confidence: 99%

“…Voorhis (1971) considered their dynamics in detail, taking thermodynamic effects into account together with the rotation of the float. Aagaard & Ewart (1973) adopted an approach similar to Winant (1974), ignoring wave radiation and retaining both linear and quadratic terms for the drag. Goodman & Levine (1990) did the same but assumed the drag to arise from steady boundary-layer dissipation, hence being quadratic for a sphere and varying as the 3/2th power of the velocity for a streamlined float.…”

Section: Introductionmentioning

confidence: 99%

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Buoyancy oscillations

Voisin

2024

J. Fluid Mech.

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The oscillations of buoyant bodies in stratified fluids are deduced from the variations of their added mass. Three configurations are considered: a body displaced from its neutral level then released; a Cartesian diver set into oscillation by a modulation of the hydrostatic pressure, then released; and a body attached to a pendulum to which an impulse is applied. The first configuration is related to the dynamics of Lagrangian floats in the ocean. Two particular bodies are considered: an elliptic cylinder of horizontal axis, typical of two-dimensional bodies; and a spheroid of vertical axis, typical of three-dimensional bodies. The ultimate motion of the body consists of oscillations at the buoyancy frequency with an amplitude decaying algebraically with time. Before that, the resonant response of the system is observed, either aperiodic exponential decay when the system has no intrinsic dynamics, or exponentially damped oscillation otherwise. Comparison with available measurements demonstrates the need to include viscous dissipation in the analysis. At high Stokes number, dissipation comes from the Basset–Boussinesq memory force and is affected negligibly by the stratification; at low Stokes number, dissipation comes from Stokes resistance and exhibits a significant effect of the stratification.

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