Chaotic advection in a steady three-dimensional MHD flow

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Main Authors: Fontchastagner, Julien, Scheid, Jean-François, Angilella, Jean-Régis, Brancher, Jean-Pierre
Format: Preprint
Published: 2024
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_version_ 1866911247657598976
author Fontchastagner, Julien
Scheid, Jean-François
Angilella, Jean-Régis
Brancher, Jean-Pierre
author_facet Fontchastagner, Julien
Scheid, Jean-François
Angilella, Jean-Régis
Brancher, Jean-Pierre
contents We investigate the 3D stationary flow of a weakly conducting fluid in a cubic cavity, driven by the Lorentz force created by two permanent magnets and a weak constant current. Our goal is to determine the conditions leading to efficient mixing within the cavity. The flow is composed of a large recirculation cell created by one side magnet, superposed to two recirculation cells created by a central magnet perpendicular to the first one. The overall structure of this flow, obtained here by solving the Stokes equations with Lorentz forcing, is similar to the tri-cellular model flow studied by Toussaint et. al. (Phys. Fluids. 7, 1995). Chaotic advection in this flow is analyzed by means of Poincaré sections, Lyapunov exponents and expansion entropies. In addition, we quantify the quality of mixing by computing contamination rates, homogeneity, as well as mixing times. Though individual vortices have poor mixing properties, the superposition of both flows creates chaotic streamlines and efficient mixing.
format Preprint
id arxiv_https___arxiv_org_abs_2405_20021
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Chaotic advection in a steady three-dimensional MHD flow
Fontchastagner, Julien
Scheid, Jean-François
Angilella, Jean-Régis
Brancher, Jean-Pierre
Fluid Dynamics
Chaotic Dynamics
Computational Physics
76D07 (Primary) 76W05, 65M60 (Secondary)
We investigate the 3D stationary flow of a weakly conducting fluid in a cubic cavity, driven by the Lorentz force created by two permanent magnets and a weak constant current. Our goal is to determine the conditions leading to efficient mixing within the cavity. The flow is composed of a large recirculation cell created by one side magnet, superposed to two recirculation cells created by a central magnet perpendicular to the first one. The overall structure of this flow, obtained here by solving the Stokes equations with Lorentz forcing, is similar to the tri-cellular model flow studied by Toussaint et. al. (Phys. Fluids. 7, 1995). Chaotic advection in this flow is analyzed by means of Poincaré sections, Lyapunov exponents and expansion entropies. In addition, we quantify the quality of mixing by computing contamination rates, homogeneity, as well as mixing times. Though individual vortices have poor mixing properties, the superposition of both flows creates chaotic streamlines and efficient mixing.
title Chaotic advection in a steady three-dimensional MHD flow
topic Fluid Dynamics
Chaotic Dynamics
Computational Physics
76D07 (Primary) 76W05, 65M60 (Secondary)
url https://arxiv.org/abs/2405.20021