oai-hal-tel-00683525v1
type: Dataset
description: During my thesis I concentrated on four different aspects of physics and magnetohydrodynamics taking place in the Earth's core. Each study is presented independently in my dissertation. The first two parts are experimental studies and the two last parts theoretical and numerical calculations. ln the first part, we study experimentally a vertical vortex of liquid metal (gallium) subject to a transverse magnetic field. We investigate the simultaneous effect of Coriolis forces (due to rotation) and Lorentz forces (due to magnetic field ) on a dynamical structure similar to those possibly present in the liquid outer core (convective geostrophic columns). Experimental measurements (fluid velocity, induced magnetic field , differences in electrical potential, temperature) are interpreted with a model providing a clear picture of t he dynamics of the vortex, as weil as a description of the electrical currents generated in the vortex. Coriolis forces tends to rigidify the fluid flow along the rotation axis whereas the main effect of the magnetic field is firstly, to severely slow down the fluid and , secondly, to increase the central part of the vortex. This increase supports the presence of large diameter convective columns in the liquid core. Experimental measurements of ohmic dissipation (Joule heating) demonstrated that large scale toroidal magnetic field in the Earth's core can not exceed 25 mT if the convective flow takes place under geostrophic columns. In the second part, we present an experiment where liquid gallium is crystallized. The goal is to understand the origin of the inner core elastic anisotropy. Experimentally, we observed the crystallization velocities and analyzed the gallium crystal texture. Elastic anisotropy measured within gallium polycrystals (ultrasonic method) showed that crystals axis orientations are not determined by heat flux direction but seemingly by initial germs orientation . Moreover, we showed that gallium texture is independent of sol…
issued: 2026-05-23T05:49:36.348481
language: fr
modified: 2026-05-23T05:49:36.348489
title: Approches experimentales et theoriques de la dynamique du noyau terrestre : tourbillon geostrophique de gallium liquide dans un champ magnetique, anisotropie et rotation de la graine, chemins d'inversion
contact point: Organization
  fn: CCSD
keyword: champ-magnetique-terrestre
keyword: cristallisation-experimentale-du-gallium
keyword: gallium
keyword: infoeu-reposemanticsdoctoralthesis
keyword: noyau-terrestre
keyword: physphysphys-geo-phphysics-physicsphysics-physicsgeophysics-physicsgeo-ph
keyword: sdemcgenvironmental-sciencesglobal-changes
keyword: sdustugpsciences-of-the-universe-physicsearth-sciencesgeophysics-physicsgeo-ph
keyword: theses
keyword: tourbillon-de-gallium
landing page: https://theses.hal.science/tel-00683525

https://rec.harvest-normandie.data4citizen.com/dataset/oai-hal-tel-00683525v1/resource/0d63e5ee-660d-43af-8627-f81807fe9fa1
type: Distribution
format: HTML
issued: 2026-05-23T05:49:36.364772
modified: 2026-05-23T05:49:36.299905
title: Approches experimentales et theoriques de la dynamique du noyau terrestre : tourbillon geostrophique de gallium liquide dans un champ magnetique, anisotropie et rotation de la graine, chemins d'inversion
access URL: https://theses.hal.science/tel-00683525

test_moissonnage_selune
type: Agent