Large-scale anisotropy in stably stratified rotating flows

• Autores: Marino, R.; Mininni, Pablo Daniel; Rosenberg, D. L.; Pouquet, A.
• Año de publicación: 2014
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Stratification; Anisotropic Flows; Turbulence; Boussinesq Flows
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

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 1024 3 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.
Fil: Marino, R.. National Center for Atmospheric Research; Estados Unidos. University Of California Berkeley; Estados Unidos
Fil: Mininni, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina
Fil: Rosenberg, D. L.. National Center for Computational Sciences; Estados Unidos
Fil: Pouquet, A.. National Center for Atmospheric Research; Estados Unidos. State University Of Colorado Boulder; Estados Unidos