IFIBA   22255
INSTITUTO DE FISICA DE BUENOS AIRES
Unidad Ejecutora - UE
artículos
Título:
Large scale anisotropy in stably stratified flows
Autor/es:
R. MARINO; P.D. MININNI; D. ROSENBERG; A. POUQUET
Revista:
PHYSICAL REVIEW E
Editorial:
AMER PHYSICAL SOC
Referencias:
Lugar: New York; Año: 2014 vol. 90 p. 2301801 - 2301810
ISSN:
1539-3755
Resumen:
We present results from direct numerical simulations of the Boussinesq
equations in the presence of rotation and/or stratification, both in the
vertical direction. The runs are forced isotropically and randomly at
small scales and have spatial resolutions of up to 10243 grid points and Reynolds numbers of ≈1000.
We first show that solutions with negative energy flux and inverse
cascades develop in rotating turbulence, whether or not stratification
is present. However, the purely stratified case is characterized instead
by an early-time, highly anisotropic transfer to large scales with
almost zero net isotropic energy flux. This is consistent with previous
studies that observed the development of vertically sheared horizontal
winds, although only at substantially later times. However, and unlike
previous works, when sufficient scale separation is allowed between the
forcing scale and the domain size, the kinetic energy displays a
perpendicular (horizontal) spectrum with power-law behavior compatible
with ∼k−5/3⊥,
including in the absence of rotation. In this latter purely stratified
case, such a spectrum is the result of a direct cascade of the energy
contained in the large-scale horizontal wind, as is evidenced by a
strong positive flux of energy in the parallel direction at all scales
including the largest resolved scales.