Nonlinear vortex structures in obliquely rotating stratified fluids driven by small scale non helical forces

TL;DR

This paper investigates a novel large-scale instability in obliquely rotating stratified fluids driven by small-scale non-helical turbulence, revealing nonlinear vortex structures and Beltrami wave solutions.

Contribution

It introduces a new type of large-scale instability mechanism in stratified rotating fluids with non-helical turbulence, using multiscale asymptotic analysis.

Findings

Discovery of nonlinear Beltrami wave solutions.

Identification of localized vortex structures as kinks.

Analysis of linear instability and stationary nonlinear modes.

Abstract

In this paper, we study a new type of large-scale instability in obliquely rotating stratified fluids with small scale non-helical turbulence. The small-scale turbulence is generated by the external force with zero helicity and low Reynolds number. The theory uses the method of multiscale asymptotic developments. The nonlinear equations for large scale motions are obtained in the third order of the perturbation theory. In this paper, we consider the linear instability and the stationary nonlinear modes. We obtain solutions in the form of nonlinear Beltrami waves and localized vortex structures as kinks of new type.