Experiments on convection in a rotating hemispherical shell: Transition to chaos

Abstract

Thermal convection in a self‐gravitating rotating fluid shell is modeled using a hemispherical fluid shell that can be rotated about its axis of symmetry. In this apparatus, a tertiary convective state begins to exist at a Rayleigh number approximately equal to 2.1 times the critical value for the onset of convection ( R C1 ). This state is characterized by the coexistence of three waves. In this tertiary state noise is always present. At a slightly higher Rayleigh number, a strong interaction was observed to develop. Frequency locking takes place at 2.4 R C1 . Later, the flow exhibits chaotic behavior as shown by the broad band Fourier spectra of the temperature records. Planetary implications of these findings are discussed.