Experimental observation of steady inertial wave turbulence in deep rotating flows

Abstract

Developing a theory that describes rotating turbulence has so far proved challenging. Now, experiments show signatures of inertial waves in rotating turbulence, implying that such flow can be thought of as resulting from interacting inertial waves—solutions of the linearized rotating Navier–Stokes equation. The theoretical framework that should be used for describing rotating turbulence1,2,3 is the subject of an active debate. It was shown experimentally4,5 and numerically6,7 that the formalism of 2D turbulence is useful in the description of many aspects of rotating turbulence. On the other hand, theoretical and numerical work suggests that the formalism of wave turbulence8,9,10 should provide a reliable description of the entire 3D flow field11,12,13,14,15. The waves that are suggested as the basis for this turbulence are Coriolis-force-driven inertial waves1. Here we present experimental results that suggest the existence of inertial wave turbulence in deep steady rotating turbulence. Our measurements show energy transfer from the injection scale to larger scales, although the energy spectra are concentrated along the dispersion relation of inertial waves. The turbulent fields are, therefore, well described as ensembles of 3D interacting inertial waves.