Large-scale structure generation by anisotropic small-scale flows

Abstract
Direct numerical simulation techniques are used to study the effect of spontaneous symmetry breaking leading to the phenomenon of large‐scale secondary flow generation by anisotropic small‐scale flow. It is shown that anisotropy is a major factor that determines the ability of the small‐scale flow to generate the inverse energy cascade, that the large‐scale secondary flow is strongly anisotropic—almost unidirectional, and that the helical property of the primary flow is irrelevent. The pairing instability and long‐wave modulation of the subharmonic are important in the process of generation of the large‐scale structure.