Time-Dependent Modes of Behavior of Thermally Driven Rotating Fluids

Abstract

The characteristics of amplitude vacillation, structural vacillation and geostrophic turbulence in two thermally driven rotating fluids with different viscosities are investigated. The data presented correspond to experiments performed at four points in dimensioniess-parameter space selected to illustrate the nature of these phenomena. They include synoptic temperature distributions, radial cross sections, time- averaged temperature variance spectra, and time and space variations of the eddy temperature variance as a function of wavenumber. Amplitude vacillation is characterized by periodic growth and decay of the temperature variance associated with a single azimuthal wavenumber and its immediate sidebands. Structural vacillation is characterized by almost periodic, modulated, radial redistributions of eddy temperature variance associated with a single azimuthal wavenumber and its higher harmonics, with little variation in the volume integrated eddy temperature variance. Geostrophic turbulence is characterized by a broad spectrum of azimuthal wavenumbers with irregular behavior. At high wavenumbers, the temperature variance spectra in geostrophic turbulence display different slopes depending on the location of the experiment in dimension-less-parameter space.