CCP-NTH Webinar: Sidewall Effects in the Transition to Turbulence in Magnetoconvection

CCP-NTH Webinar: Sidewall Effects in the Transition to Turbulence in Magnetoconvection

🗓️ Date: Friday, 30 May 2025

🕐 Time: 13:30–14:30 BST (UTC+1), UK London Time

🎙️ Host: Dr. Wei Wang, CoSeC CCP-NTH, UKRI-STFC

🧑‍🏫 Speaker: Matthew McCormack, University of Edinburgh

🔬 Topic: Sidewall Effects in the Transition to Turbulence in Magnetoconvection

Abstract: 

With nuclear fusion aiming to revolutionise energy production, there has been growing interest in high-performance liquid metal cooling systems and by extension, in liquid metal magnetoconvection – where an electrically conducting layer of fluid is driven by an imposed vertical temperature gradient in the presence of an applied magnetic field. Traditional theoretical work predominantly considers laterally periodic domains, a simplification which aligns with geo-astrophysical applications. However, the presence of rigid sidewalls, intrinsic to industrial cooling systems, leads to qualitatively different dynamics and instability mechanisms in the flow. In this seminar, I will present recent results on the transition to turbulence in liquid metal magnetoconvection in laterally confined geometries. Contrary to the supercritical transition observed in idealised, laterally periodic domains, we find that sidewalls induce a subcritical transition, leading to multiple stable states and hysteretic effects as control parameters are varied. This behaviour is connected to wall modes – coherent structures localised near the sidewalls – which fundamentally alter the bifurcation structure and spatiotemporal dynamics of the flow, even in turbulent regimes. These wall modes enhance convective heat transport and underpin the observed multistability. This offers potential pathways for flow control that may enable the system to be manipulated into high-efficiency heat transport regimes under identical operating conditions, with implications for the operation of liquid metal cooling systems. 

A short biography of the speaker:

Matthew McCormack is a PhD student in the School of Mathematics and the Maxwell Institute for Mathematical Sciences at the University of Edinburgh. He received a BE in Mechanical Engineering from University College Dublin in 2021 and an MSc in Computational Methods for Aeronautics from Imperial College London in 2022. In 2024, he completed a fellowship in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution. He conducts research in theoretical fluid dynamics and magnetohydrodynamics, with an emphasis on multiscale nonlinear dynamical systems.