Geophysical & Astrophysical Fluid Dynamics Seminar Series

Title：Numerical Simulation of Planetary Dynamo in the Inviscid Limit

Speaker：Longhui Yuan (ETH Zurich)

Location: Middle conference room, 3rd floor

Time：10:00 am July 17, 2025 (Thu)

Abstract:
Earth’s magnetic field is generated and maintained over billions of years by the geodynamo process, governed by a set of highly nonlinear, coupled partial differential equations that can only be solved numerically. However, the overwhelming dominance of the Coriolis force over viscous and inertial effects in Earth’s core makes direct numerical simulations (DNS) in Earth-like regimes extremely challenging. I will present the current status of the first 3D inviscid convective geodynamo model developed in a full-sphere geometry. This model has the potential to offer new insights into the dynamo of Earth (and other planets) that are difficult to access using conventional DNS. I will also present results on inviscid torsional oscillations, which serve as a simple testbed for inviscid magnetohydrodynamic (MHD) computations in a spherical shell geometry. A theoretically plausible and previously unrecognized class of torsional normal modes will be discussed. An encouraging result is that, when viscosity is retained, decreasing the Ekman number leads to convergence toward the inviscid solution.

Bio:
Longhui Yuan received his B.S. degree from the Southern University of Science and Technology in 2020 and his M.Phil. degree from the University of Hong Kong in 2022. Since January 2023, he has been pursuing a Ph.D. at ETH Zurich. His research interests span a broad range of topics in Earth and planetary sciences, including planetary interior dynamics, orbital evolution of exoplanetary systems.