PI: Robert Teed

Our project highlight was the research conducted using DiRAC that led to the publication:

Teed, Robert J. and Dormy, Emmanuel (2025) Scaling of strong-field spherical dynamos. Geophysical Research Letters, 52(20), (doi: 10.1029/2025GL118078)

For this work we used approximately 200 kCPUh of time on DiRAC.

Numerical experiments of dynamo action are designed to understand the generation of Earth’s dipolar magnetic field by complex fluid motions within Earth’s molten core. Simulations of this process produce different regime branches identified within bifurcation diagrams. Notable are distinct solutions where the resultant magnetic field is either weak or strong. Weak-field solutions are identified by the prominent role of viscosity on the motion, whereas the magnetic field has a leading-order effect on the flow in strong-field solutions.

The image below shows contour plots from two different regimes found in spherical dynamo simulations produced using DiRAC. In both the “weak-field” regime (left column) and “strong-field” regime (right column), the surface magnetic field (top row) is dominantly dipolar (blue and red in opposite hemispheres), but the fluid flow (bottom row) differs drastically.

By using the HPC of DiRAC we were able to demonstrate the persistence of the strong-field branch at low values of viscosity that would not otherwise be possible on local computer clusters. Production of models on the strong-field branch and providing scaling laws governing its existence as parameters move toward values appropriate for the Geodynamo is vital to further understand Earth’s core. In this work we introduced a new simulation output parameter that identifies strong-field solutions throughout input parameter space. This new measure and the bounds on scaling laws we produced will guide future studies in locating strong-field dynamos in parameter space.