Transport by 2D turbulence: Vortex-Gas Theory vs Scale-Invariant Inverse Cascade
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Le 17/06/2025, de 11:00 à 12:00 |
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| Participants |
Julie Meunier |
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The Kraichnan-Leith-Batchelor (KLB) inverse energy cascade is a hallmark of 2D turbulence, observed in Direct Numerical Simulations (DNS) forced near the maximum resolved wavenumber. However, when simulating 2D flows forced at intermediate scale and damped by weak linear or quadratic drag, we observe that the turbulent flow's transport properties significantly deviate from the KLB predictions. We derive alternate scaling predictions for the flow's effective diffusivity based on the emergence of intense, isolated vortices causing spatially intermittent frictional dissipation localized within the small vortex cores. The predictions quantitatively match DNS data. This study points to a universal behavior of 2D turbulence that departs from the standard KLB phenomenology, thus bridging standard 2D Navier-Stokes turbulence with large-scale geophysical turbulence.