Your query was:

"OS54F-05"

HR: 16:00h
AN: OS54F-05
TI: Flows driven by mixing in the laboratory-ocean applications
AU: Stevenson, I
EM: ihs@rice.edu
AF: Department of Physics, Rice University, Houston, TX 77251 United States
AU: * Whitehead, J A
EM: jwhitehead@whoi.edu
AF: Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AB: A two-layer density-stratified fluid was turbulently mixed with a horizontally moving vertical rod. The rod ran throughout the fluid to create homogenous turbulence, and we observed the evolution of the density profiles as mixing occurred. In the highly-turbulent regime in which this study was conducted, where Reynolds Number Re > 600 and Richardson Number Ri < 0.4, step-formation does not occur. The density profile of the fluid evolved smoothly from a single step to a constant density profile in the fully mixed state. The density flux and buoyancy frequency evolve in rough agreement with that predicted by Posmentier (1977), but in the low Ri regime this data is far from conclusive. Examination of the amount of turbulent kinetic energy going into mixing agrees with previous results (Holford and Linden 1999) with a maximum of 5% of the kinetic energy contributing to the change in potential energy. Next, we propose a theoretical expression for the buoyancy flux due to turbulent mixing. Using this expression, the solutions to the equation for conservation of density collapse when a similarity variable is used. We verify this collapse experimentally for a range of Reynolds and Richardson Numbers. Finally, with this apparatus we illustrate the scaling laws applied to a laboratory experiment with a stratified fluid flux, as in the ocean. The experiment shows that some mixing is the result of the circulation. This mixing exists in addition to the mixing that drives the vertical circulation, and it corresponds to mixing by overflows in the ocean. The scaling that gives the ratio of the magnitudes of overflow to driving energy flux is discussed.
DE: 4211 Benthic boundary layers
DE: 4520 Eddies and mesoscale processes
DE: 4524 Fine structure and microstructure
DE: 4568 Turbulence, diffusion, and mixing processes
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: Ocean Sciences 2006