Berlin 2024 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 32: Poster: Active Matter, Soft Matter, Fluids

DY 32.27: Poster

Wednesday, March 20, 2024, 15:00–18:00, Poster C

Reduced order network model of incompressible magnetohydrodynamic turbulent flows — •Maria Mathew and Wolf-Christian Müller — ZAA, Technische Universität Berlin, Germany

Plasma turbulence is a widespread phenomenon in astrophysical systems. However, three-dimensional simulations of these systems with realistic parameter values present a significant challenge due to the extensive spectral bandwidth of nonlinearly interacting fluctuations within turbulent flows.

To address this, model reduction techniques have been employed to facilitate a more cost-effective approximative representation of the flow. We extend the network model ansatz newly proposed in a reduced scalar model for the energy dynamics in magnetohydrodynamic flows [Beck, Müller; arXiv:2203.11536 (physics.flu-dyn)], to encompass the dynamics of magnetic helicity, in order to obtain an easily modifiable, reduced representation of plasma turbulence. Our approach involves selecting an inherently minimal subsystem that conservatively transports energy and other quadratic invariants across wavenumber space. This network-based representation of energy-exchanging interconnected agents adeptly captures the intricate dynamics of the flow while simultaneously reducing computational complexity. Within this framework, the spectral scaling is studied, comparing it to the established phenomenological models. Additionally, the impact of various geometric constraints on our transfer function is investigated, particularly on the spectrum of magnetic helicity. We discuss our findings as well as the associated limitations.

Keywords: Turbulence; magnetohydrodynamic; network