Laboratory Experiments on Diapycnal Mixing in Stratified Fluids
Abstract
Our turbulent length scale, velocity and diffusivity scalings are compared with data from other numerical, laboratory and field experiments. Comparison is made with reference to the turbulence intensity measure epsilon/nu N squared. We showed that our turbulent length scale and velocity results are consistent with measurements from the experiments considered, and that the rms turbulent length scale L (sub t) is independent of the rate of dissipation of turbulent kinetic energy when epsilon/nu N squared > 300. A diffusivity modelled in terms of an advective buoyancy flux, b, is found to reproduce our direct measurements of K (sub rho) in the experiments considered when epsilon/nu N squared > 300. It is shown that modelling K(sub rho) as 0.2 epsilon/N squared is a poor parameterization of the advective buoyancy flux model in all the experiments considered, and that at large epsilon/nu N squared, this parameterization can over-predict the true K(sub rho) by two orders of magnitude. This over prediction is discussed in terms of a mixing efficiency and it is shown that in the experiments considered the mixing efficiency decreases rapidly with increasing epsilon/nu N squared. Finally, the application of our diffusivity scaling to other geophysical flows is discussed, and it is shown that a necessary requirement for the use of this scaling is that L)sub t) is independent of the rate of dissipation of turbulent kinetic energy.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 19, 2001
- Accession Number
- ADP013591
Entities
People
- G. N. Ivey
- J. Imberger
- K. B. Winters
- M. E. Barry
Organizations
- University of Washington