Modeling magnetized turbulence (transport, mixing, and intability growth) for nuclear fusion and astrophysics applications

• Harrison Jacob, Physics, University of Delaware

• Arijit Bose, Department of Physics and Astronomy, University of Delaware

Hydrodynamic instabilities transfer energy from ordered fluid motion into turbulent fluctuations and play a critical role in many natural and engineered systems. One of the most fundamental examples is the Rayleigh–Taylor instability (RTI), which occurs when a denser fluid is accelerated into a lighter fluid, producing complex turbulent mixing. In inertial confinement fusion (ICF), RTI-driven mixing can reduce confinement efficiency and limit fusion energy yield, making it essential to understand and predict its evolution.

This research investigates how magnetic fields influence the development of RTI by comparing hydrodynamic and magnetized simulations. High-resolution three-dimensional simulations are performed using Pyranda, an open-source Python-based solver for the compressible magnetohydrodynamic equations. We analyze instability growth, turbulent kinetic energy, and mass mixing to quantify the effects of magnetic fields on turbulence. We also evaluate Reynolds-averaged Navier–Stokes (RANS) turbulence closures and integral length scales in both magnetized and unmagnetized simulations to assess the applicability of existing turbulence models. Our results show that magnetic fields suppress the growth of turbulent kinetic energy, reduce the size of coherent turbulent structures, and slow the overall development of the instability. These findings provide insight into the physics of magnetized turbulence and support the development and validation of improved RANS turbulence models for applications in ICF and astrophysical plasmas.