Helicity in rotating convection with topography: 3D Lagrangian particle tracking in ToRoCo

Helicity, an inviscid invariant like momentum and energy, serves as a topological measure of the intertwining of vorticity and velocity in a fluid flow. Helicity plays a pivotal role in understanding many difficult problems including the geodynamo theory that concerns the Earth’s magnetic field generation through fluid motion in the outer core. Recent evidence suggesting a relatively young solid inner core challenges the classical convection-based dynamo theories and has drawn attention to alternative mechanisms, such as flow interactions with topography at the core–mantle boundary. In this work, we aim to quantify helicity using three-dimensional flow fields measured by Lagrangian particle tracking in our newly developed apparatus, ToRoCo (Topographic Rotating Convection). Looking ahead, together with complementary measurements in liquid metal experiments, we aim to bring new insights into the role of helicity in planetary flow and magnetic field generation.