Evidence for Bolgiano-Obukhov scaling in rotating stratified turbulence using high-resolution direct numerical simulations

Journal Article · Thu Jan 01 00:00:00 EST 2015 · Physics of Fluids

DOI:https://doi.org/10.1063/1.4921076· OSTI ID:1185644

Rosenberg, Duane L ^[1]; Pouquet, Dr. Annick ^[2]; Mininni, Dr. Pablo D. ^[3]; Marino, Dr. Raffaele ^[2]

---

1. ORNL
2. National Center for Atmospheric Research (NCAR)
3. Universidad de Buenos Aires, Argentina

We report results on rotating stratified turbulence in the absence of forcing, with large-scale isotropic initial conditions, using direct numerical simulations computed on grids of up to $4096^3$ points. The Reynolds and Froude numbers are respectively equal to $$Re=5.4\times 10^4$$ and $Fr=0.0242$$. The ratio of the Brunt-V\"ais\"al\"a to the inertial wave frequency, $$N/f$, is taken to be equal to 5, a choice appropriate to model the dynamics of the southern abyssal ocean at mid latitudes. This gives a global buoyancy Reynolds number $$R_B=ReFr^2=32$$, a value sufficient for some isotropy to be recovered in the small scales beyond the Ozmidov scale, but still moderate enough that the intermediate scales where waves are prevalent are well resolved. We concentrate on the large-scale dynamics and confirm that the Froude number based on a typical vertical length scale is of order unity, with strong gradients in the vertical. Two characteristic scales emerge from this computation, and are identified from sharp variations in the spectral distribution of either total energy or helicity. A spectral break is also observed at a scale at which the partition of energy between the kinetic and potential modes changes abruptly, and beyond which a Kolmogorov-like spectrum recovers. Large slanted layers are ubiquitous in the flow in the velocity and temperature fields, and a large-scale enhancement of energy is also observed, directly attributable to the effect of rotation.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1185644
• Journal Information: Physics of Fluids, Vol. 27, Issue 5; ISSN 1070--6631
• Country of Publication: United States
• Language: English

Related Subjects

turbulence
Bolgiano-Obukhov
direct numerical simulation
convective instabilities