Numerical simulations of baroclinic driven flows in a thermally driven rotating annulus using the immersed boundary method

Abstract

We present results of numerical simulations of baroclinic driven flows in the thermally driven rotating annulus using the immersed boundary method for modeling of the boundary conditions. The Navier-Stokes equations in the Boussinesq approximation are solved in the Eulerian flux-form advection scheme with the geophysical flow solver EULAG as numerical framework. We test our approach against results of an appropriate laboratory experiment with water as working fluid and directly aim at the wavy flow regime where complex flows and regular wave patterns are generally observed but where centrifugal effects and turbulence is of minor importance. Multivariate statistical methods are used for analyzing time series of computed temperature data. We, here, present the outcome of the time series data analysis at particular parameter points, and specifically analyze a complex wave-wave interaction, and, secondly, a wave mode switch where the azimuthal wave number changes to the next higher one. The numerical results are highly consistent with the experimental observations. That encourage us to focus on our actual goal as the next step, that is the irregular flow regime found at large rotation rates where the centrifugal force has an increasing effect on flow states and where multiple scale flows are generally observed.

Keywords

• baroclinic driven flows
• thermally driven rotating annulus
• numerical experiments
• immersed boundary method
• complex flow regimes
• multivariate time series analysis