Testing the Assumptions Underlying Ocean Mixing Methodologies Using Direct Numerical Simulations
Abstract
Direct numerical simulations of stratified turbulence are used to test several fundamental assumptions involved in the Osborn, Osborn–Cox, and Thorpe methods commonly used to estimate the turbulent diffusivity from field measurements. The forced simulations in an idealized triply periodic computational domain exhibit characteristic features of stratified turbulence including intermittency and layer formation. When calculated using the volume-averaged dissipation rates from the simulations, the vertical diffusivities inferred from the Osborn and Osborn–Cox methods are within 40% of the value diagnosed using the volume-averaged buoyancy flux for all cases, while the Thorpe-scale method performs similarly well in the simulation with a relatively large buoyancy Reynolds number (Reb ≃ 240) but significantly overestimates the vertical diffusivity in simulations with Reb irreversible buoyancy flux.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 01, 2019
- Source ID
- 10.1175/jpo-d-19-0033.1
Entities
People
- C. P. Caulfield
- J. R. Taylor
- P. F. Linden
- Stephen M. de Bruyn Kops
Organizations
- Engineering and Physical Sciences Research Council
- Office of Naval Research
- University of Cambridge
- University of Massachusetts Amherst