Kinematic dynamo models from hydrodynamic simulations and experiments of precession driven flows

We used a model water experiment and hydrodynamic simulations to estimate the flow in a precessing cylinder. The resulting velocity fields are dominated by standing inertial waves which makes them appropriate for the application in a kinematic dynamo model based on the time-averaged flow. We found dynamo action at magnetic Reynolds numbers of the order of Rm~500.
Essential for the dynamo is the coupling of the primary (directly forced) flow with azimuthal wave number m = 1 and a non-geostrophic axisymmetric mode which at Re = 10000 emerges in a narrow regime around Po = 0.10.

Our results point out a first promising – but narrow – regime
where we may expect dynamo action in the large scale dynamo
experiment currently under construction at HZDR.