ISTerre - Institut des Sciences de la Terre

ERC project THEIA

David CÉBRON, Jérémie VIDAL, Max SOLAZZO — 2022-02-14T07:38:21Z

Project	About Us	Publications	Communications	Numerics	Experiments	Gallery

Rotating flows over relief

Flow over boundary relief generates waves and changes the forces on the surrounding solid. Laboratory experiments allow the geometry and rotation to be varied independently, and give access to flow regimes that are expensive to simulate.

Rotating-fluid apparatus at ISTerre

Led by David Cébron, THEIA's experimental programme moved from the original plan to use the CORIOLIS platform to a dedicated facility at ISTerre. The programme developed the WEBER rotating system, tank designs, rotation control, optical access and particle image velocimetry (PIV), which measures velocity in a plane from successive images of illuminated tracer particles.

The apparatus was developed at two working scales:

– mini-THEIA, approximately 50 cm across, provided a compact testbed for developing measurement procedures and investigating rotating flows over a physical rough bottom.
– The intermediate THEIA tank, approximately one metre across, mounted on WEBER, was used to develop rotation control, calibration and acquisition procedures, and for PIV spin-up experiments.

David Cébron and Max Solazzo jointly conceived and designed the THEIA and mini-THEIA experiments. Max Solazzo, a permanent CNRS engineer at ISTerre, carried out the CAD, mechanical construction and assembly.

THEIA experimental apparatus at ISTerre

Intermediate THEIA tank on the WEBER rotating platform at ISTerre, Grenoble.

The gallery shows the one-metre tank on WEBER in daylight and under laser illumination, mini-THEIA's rough bottom, and the contributions to mechanical design and assembly.

Spin-up and topographic coupling

After a change in the container's rotation rate, the fluid adjusts through an exchange of angular momentum with the boundaries. Comparing this spin-up over smooth and rough bottoms helps isolate the contribution of relief. Baptiste Penlou developed PIV acquisition and analysis procedures for these comparisons in the intermediate tank, following earlier experimental work, including Samuel Payen's contribution in 2025.

Particle image velocimetry in THEIA

Intermediate THEIA rotating tank illuminated by a laser sheet for particle image velocimetry (PIV). ISTerre, Grenoble.

The photograph shows the laser illumination used for PIV, not a processed velocity field.

The overall spin-up rate and the evolution of the radial velocity profile describe different aspects of this adjustment. Their interpretation requires accounting for boundary friction, waves and measurement uncertainties. The smooth- and rough-bottom PIV measurements remained unpublished at the end of the ERC action. They are not presented here as quantitative validation of a universal drag law.

The Giraud et al. (2026) study compares theory and direct simulations with the spin-up measurements published by Burmann and Noir in 2018. Its experimental comparison concerns those earlier data, separate from the work in THEIA's one-metre tank.

Acoustic measurements

Collaborative work on modal acoustic velocimetry for libration-driven flows used acoustic resonances in the gas-filled ZoRo spheroid. Acoustic measurements complement optical methods where particle imaging is difficult. The publisher's correction accompanies the article.

See the project results, numerical methods, team contributions and gallery.

ERC project THEIA

David CÉBRON, Jérémie VIDAL, Max SOLAZZO — 2022-02-10T09:07:26Z

Project	About Us	Publications	Communications	Numerics	Experiments	Gallery

Numerical methods

Local models calculate the stresses generated by flow over relief; global spectral methods resolve modes and instabilities in ellipsoids; direct simulations follow nonlinear fluid and magnetic evolution. THEIA, led by David Cébron at ISTerre, used these complementary approaches within the geometries and boundary conditions described in the associated papers.

ToCCo — local topographic coupling

ToCCo, developed by Rémy Monville during THEIA, calculates weakly nonlinear flows over periodic topography. The modelled configurations include rotation, buoyancy, magnetic effects, curvature and confinement. Symbolic calculations and arbitrary-precision arithmetic are used to obtain pressure, viscous and electromagnetic stresses within a perturbative approach. Fully developed turbulence over arbitrary roughness is outside its scope.

The public repository carries the CeCILL 2.1 licence. The 2024 archived release provides a persistent citation. The core–mantle application was developed by Rémy Monville, David Cébron and Dominique Jault (2025).

Ellipsoidal modes and stability

Jérémie Vidal developed and extended polynomial spectral methods for rotating fluids in ellipsoids. During THEIA, this work formed part of his research with David Cébron on modes, mechanically forced flows and magnetic induction in non-spherical cores. His numerical-tools page describes the methods and reference papers:

SHINE calculates diffusionless hydromagnetic eigenmodes of Boussinesq fluids and non-magnetic modes of compressible fluids in co-rotating triaxial ellipsoids. THEIA extended this modelling programme from its earlier foundations. Documentation and references are available on the author's numerical-tools page.
SWAN performs short-wavelength linear stability analysis of Cartesian basic states, giving sufficient conditions for local instability. The public repository contains documentation and the hydrodynamic archive v0_nomag.zip in Downloads, with a CeCILL 2.1 licence specified in the README. This archive covers the hydrodynamic version; it does not supply the complete magnetic version. The method predates THEIA.
SIREN tests the global linear stability of uniform-vorticity flows in ellipsoids using polynomial perturbations and inertial modes. The method predates THEIA. Documentation and references are available on the author's numerical-tools page.

The 2021 kinematic dynamo paper by Vidal and Cébron gives a spectral induction method and benchmarks with local magnetic boundary conditions. Here the velocity is prescribed, without magnetic feedback. This differs both from SHINE's diffusionless eigenmode problem and from a self-consistent nonlinear dynamo. Other applications concern precession-driven flows in stress-free ellipsoids and acoustic modes with centrifugal gravity.

Kinematic dynamo in a triaxial ellipsoid

Magnetic-field amplitude in a triaxial ellipsoid, obtained for a prescribed flow with insulating magnetic boundary conditions. From Vidal & Cébron, Proceedings of the Royal Society A (2021), Fig. 9b.

XSHELLS and collaborative simulations

XSHELLS, developed by Nathanaël Schaeffer, solves rotating incompressible flows and magnetic fields in spherical shells and full spheres. It uses spherical harmonics and radial discretisation and is distributed under the CeCILL licence. Its website provides the source repository, documentation and benchmark references.

THEIA used this existing spherical solver and contributed developments and test cases for topographic and magnetohydrodynamic applications. Collaborative applications include semi-convective dynamos, studied by Paul Pružina, Nathanaël Schaeffer and David Cébron, and inner-core oscillation damping, studied by Paolo Personnettaz, David Cébron, Nathanaël Schaeffer, Renaud Deguen and Mioara Mandea.

The Giraud et al. study used the external solver Nek5000 for direct simulations at ETH Zürich.

Software and references

The software repositories and reference publications are linked above. For reuse, follow the authors' documentation and cite the relevant software release and method papers. The Publications page provides further details of the scientific applications and full authorship.

See also the project results and experimental methods.

ERC project THEIA

David CÉBRON, Jérémie VIDAL, Max SOLAZZO — 2022-02-10T09:01:26Z

Project	About Us	Publications	Communications	Numerics	Experiments	Gallery

Selected presentations and scientific meetings

43 selected scientific communications (2020–2026)

This curated record brings together conference presentations, invited seminars, posters and scientific workshop contributions by current and former THEIA team members and collaborators. Each entry documents a presentation, including cases where related results were presented at different meetings. The selection covers research carried out within, or scientifically related to, THEIA; inclusion does not imply that every communication was funded by ERC THEIA.

- 2026 -

43. Cébron D., High-performance simulations of turbulent planetary dynamos
Journées 2026 de la Société Française d'Astronomie et d'Astrophysique (SF2A), Grenoble (France), June 22-26, 2026.

42. Vidal J. & Colin de Verdière Y., Inertia-gravity waves in geophysical vortices
Workshop 'Vortices and vorticity in geophysical flows', Institut Henri Poincaré, Paris (France), April 20-24, 2026. Poster.

41. Pružina P., Cébron D., Schaeffer N., Dynamos planétaires générées par la semi-convection dans les couches stratifiées
29th Rencontre du Non-Linéaire, Université Paris Cité, Paris (France), March 25, 2026. Poster and short presentation (presented by P. Pružina).

40. Cébron D., Dynamics of the core and dynamo
Planetary Atmospheres and Interiors: A Two-Way Connection, Winter School, Les Houches (France), February 8–13, 2026. Lecture and member of the scientific and organizing committee.

39. Vidal J., Did lunar tides sustain the early Earth's dynamo?
DFG Seminar, Institut de Physique du Globe de Paris (France), January 13, 2026. Invited seminar.

- 2025 -

38. Cébron D., Couplage fluide à la frontière noyau-manteau
30 ans de l'IRPHE, Marseille (France), December 5, 2025. Invited scientific talk.

37. Vidal J., The Legend of Archean Zircons: A Link To The Past Moon's Tides?
Journée du Conseil Scientifique de l'Observatoire de Lyon (OSUL), Lyon (France), November 28, 2025. Scientific presentation.

36. Giraud V., Noir J., Monville R., Vidal J. & Cébron D., Inertial wave drag generated by topography
Workshop 'Fluid flow and magnetic dynamos: From the laboratory to the stars and planets', Centro Stefano Franscini, Ascona (Switzerland), September 14-19, 2025. Poster.

35. Personnettaz P., Meresse A., Cébron D., Schaeffer N., Laminar to turbulent transition in librating spheres
2nd European Fluid Dynamics Conference (EFDC2), Dublin (Ireland), August 26-29, 2025.

34. Giraud V., Noir J., Cébron D., Monville R. & Burmann F., Investigating the drag force due to inertial waves generated by topography
EGU General Assembly 2025, Vienna (Austria), April 27-May 2, 2025. Abstract EGU25-7333.

33. Cébron D., Unravelling the dynamics of non-spherical planetary cores
Thème Intérieurs de la Terre et des planètes, invited seminar at IPG Paris (France), April 3, 2025.

32. Vidal J., When boundaries matter, the case of inertia-gravity modes
Advanced Summer School on Mathematical Fluid Dynamics, Institut d'Études Scientifiques de Cargèse (France), March 31-April 12, 2025. Invited lecture.

31. Monville R., Cébron D. & Jault D., Topographic drag at the core-mantle interface
IPAM Workshop 'Rotating Turbulence: Interplay and Separability of Bulk and Boundary Dynamics', Los Angeles (USA), January 27-31, 2025. Poster.

- 2024 -

30. Personnettaz P., Monville R., Schaëffer N., Cébron D., Mandea M., Beyond spherical boundaries in deep fluid layers of planets
1st European Fluid Dynamics Conference (EFDC1), Aachen (Germany), September 16-20, 2024.

29. Vidal J., Dynamics of pancake-like geophysical vortices: from waves to (bulk) turbulence?
10th International Symposium on Bifurcations and Instabilities in Fluid Dynamics (BIFD), University of Edinburgh (UK), June 24-28, 2024. Research talk.

28. Giraud V., Noir J., Burmann F. & Cébron D., Numerical and experimental investigation on the effect of topography on the hydrodynamics of planetary fluid envelops
EGU General Assembly 2024, Vienna (Austria), April 14-19, 2024. PICO presentation, abstract EGU24-7843.

27. Personnettaz P., Schaëffer N., Cébron D., Mandea M., Fluid response to the inner core's translational oscillations
Rencontres du Non-Linéaire, Paris, March 19-20, 2024.

26. Monville R., Cébron D. & Jault D., Topographic effects in planetary magneto-hydrodynamic flows
Rencontres du Non-Linéaire, Paris, March 19-20, 2024. PDF

25. Vidal J. & Colin de Verdière Y., Inertia-gravity waves, a canonical example of nonlinear eigenvalue problems
27th Rencontre du Non-Linéaire, Université Paris Cité, Paris (France), March 18-20, 2024. Poster.

24. Vidal J., Inertia-gravity waves in geophysical vortices
Seminar, Institut de Mathématiques de Bourgogne, Université de Bourgogne (France), February 20, 2024. PDF

23. Vidal J., Ondes d'inertie-gravité dans un fluide confiné, applications géophysiques
Seminar "MathsInFluids" - UMPA, ENS Lyon (France), February 2, 2024. PDF

- 2023 -

22. Monville R., Cébron D. & Jault D., Topography-driven flows in magnetized planetary layers
GRACEFUL scientific meeting, Toulouse (France), November 22-23, 2023. Scientific talk on topographic coupling (cross-project meeting).

21. Vidal J., Inertia-gravity waves in geophysical vortices
"Spectral and Resonance Problems for Imaging, Seismology and Materials Science", Université de Reims Champagne-Ardenne (France), November 20-24, 2023. PDF

20. Cébron D., Simulations of non-spherical liquid cores of planets
Beyond Boussinesq for Astrophysical and Geophysical fluids: Numerical tools and experiments of the future. ENS Lyon, France, October 19, 2023.

19. Personnettaz P., Cébron D., Schaëffer N., Mandea M., Dissipation mechanisms of the inner core's translational oscillations
Journées CNES (JC2) 2023, Toulouse (France), October 11-13, 2023.

18. Personnettaz P., Cébron D., Schaëffer N., Mandea M., Modeling non-spherical effects with parametrized boundary conditions
GAFDEM: Geophysical Astrophysical Fluid Dynamics: Experiments and models, Nice (France), September 11-15, 2023.

17. Monville R., Vidal J., Cébron D. & Schaeffer N., Topographic coupling at the core mantle boundary
28th General Assembly of The IUGG, Berlin (Germany), July 11-20 2023. PDF

16. Monville R., Vidal J., Cébron D. & Schaeffer N., Rotating double-diffusive convection: Flows and dynamos in stably stratified deep layers of planets
28th General Assembly of the IUGG, Berlin (Germany), July 11–20, 2023.

15. Cébron D., Monville R., Vidal J. & Schaeffer N., Generation of planetary core zonal flows by orbital forcings or fingering convection
28th General Assembly of the IUGG, Berlin (Germany), July 11–20, 2023.

14. Vidal J. & Cébron D., Precession-driven flows and turbulence in planetary liquid cores
28th General Assembly of The IUGG, Berlin (Germany), July 11-20 2023. PDF

13. Vidal J. & Cébron D., Asymptotic models of rotating flows in stress-free ellipsoids
26eme Rencontre du Non Linéaire, Paris (France), March 28-30 2023. PDF

- 2022 -

12. Monville R., Cébron D., Schaeffer N., Topographic Effects in Magnetized and Stratified Fluid Cores
AGU Fall Meeting, Chicago (USA), December 12-16 2022.

11. Monville R., Vidal J., Cébron D., Schaeffer N., Rotating Double-Diffusive Convection: Flows and Dynamos in Stably Stratified Deep Layers of Planets
AGU Fall Meeting, Chicago (USA), December 12-16 2022. PDF

10. Monville R., Cébron D., Jault D., Topographic effects in magnetized and stratified fluid cores,
17th Symposium of SEDI, ETH Zurich (Switzerland), July 11- July 15 2022.

9. Cébron D., Monville R., Vidal J., Sauret A., Schaeffer N., Generation of planetary core zonal flows by mechanical forcings & fingering convection
17th Symposium of SEDI, ETH Zurich (Switzerland), July 11- July 15 2022.

8. Vidal J., Cébron D., Asymptotic models of rotating flows in ellipsoidal planets
17th Symposium of SEDI, ETH Zurich (Switzerland), July 11- July 15 2022.

7. Monville R., Cébron D., Jault D., Topographic effects in magnetized and stratified fluid cores
17th Colloque quadriennal de bilan et prospective du PNP, ENS Lyon (France), June 29- July 1 2022.

6. Cébron D., Monville R., Vidal J., Sauret A., Schaeffer N., Generation of planetary core zonal flows by mechanical forcings & fingering convection
Colloque quadriennal de bilan et prospective du PNP, ENS Lyon (France), June 29- July 1 2022.

5. Vidal J. & Cébron D., Asymptotic models of rotating flows in ellipsoidal planets
Colloque quadriennal de bilan et prospective du PNP, ENS Lyon (France), June 29- July 1 2022.

- 2021 -

4. Monville R., Cébron D., Jault D., Topographic effects in a stratified layer at the top of the Earth's core
Workshop Grenoble-Zurich-Marseille-ROB, ETH Zurich (Switzerland), November 16 2021.

3. Vidal J. & Cébron D., Kinematic dynamos in triaxial ellipsoids
Workshop Grenoble-Zurich-Marseille-ROB, ETH Zurich (Switzerland), November 16 2021.

2. Monville R., Cébron D., Jault D., Topographic effects at the core-mantle boundary
International conference IAGA-IASPEI 2021, Hyderabad (India), 21-27 August 2021.

- 2020 -

1. Schaeffer N., Cébron D., Vidal J., Noir J. & Monville R., Investigations on precession, tides, convection and stratification in planetary cores
ISSI Workshop 'Probing the Deep Earth Interior by using in synergy observations of the Earth's gravity and magnetic fields, and of the Earth's rotation', Bern (Switzerland), September 1-4, 2020. Early scientific context for THEIA.

ERC project THEIA

David CÉBRON, Jérémie VIDAL, Max SOLAZZO — 2022-02-09T07:48:38Z

Project	About Us	Publications	Communications	Numerics	Experiments	Gallery

Publications associated with THEIA

This bibliography includes 23 peer-reviewed scientific publications relevant to THEIA: 20 articles in the main project bibliography, two additional collaborative papers explicitly acknowledging ERC THEIA support, and one earlier methodological paper published in 2020, before the project began.

Several articles accepted during THEIA were published after the project's completion on 31 August 2026.

2026

Magnetohydrodynamic drag on an oscillating sphere in a rotating spherical cavity
D. Cébron, P. Personnettaz. Journal of Fluid Mechanics 1045, A13 (2026). Author manuscript / repository. Published online 15 October 2026; accepted during THEIA.

Semi-convection in rotating spherical shells: flows, layers and dynamos
P. Pružina, N. Schaeffer, D. Cébron. Journal of Fluid Mechanics 1044, A1 (2026). Author manuscript / repository. Accepted 22 July 2026; published online 30 September 2026.

Topographic drag in rapidly rotating fluids
V. Giraud, J. Noir, D. Cébron, J. Vidal, R. Monville. Journal of Fluid Mechanics 1040, A14 (2026).

Did lunar tides sustain the early Earth's dynamo?
J. Vidal, D. Cébron. Comptes Rendus. Géoscience 358 (G1), 1–26 (2026). Author manuscript / repository.

Ohmic and viscous damping of inner core translational oscillations
P. Personnettaz, D. Cébron, N. Schaeffer, R. Deguen, M. Mandea. Earth and Planetary Science Letters 690, 120156 (2026). Data and figure scripts.

The spectrum of the Poincaré operator in an ellipsoid
Y. Colin de Verdière, J. Vidal. Journal of Spectral Theory 16 (3), 751–776 (2026). Author manuscript / repository. First published online in 2025; assigned to volume 16 (2026).

2026 — Other collaborative publications acknowledging THEIA support

The two articles below explicitly acknowledge ERC THEIA (grant agreement No. 847433) in support of Paolo Personnettaz. They concern related collaborations and are distinguished from the core scientific bibliography above. The Jault et al. article also acknowledges ERC GRACEFUL (grant No. 855677).

Viscous and magnetic boundary layers at the top of the core in geodynamo models
D. Jault, P. Personnettaz, N. Gillet, T. Lepage, N. Schaeffer. Journal of Geophysical Research: Solid Earth 131 (7), e2025JB033648 (2026). Data and code. Published 2 July 2026. THEIA support acknowledged for P. Personnettaz (jointly with GRACEFUL).

Effect of split endcaps on the flow dynamics in a tall Taylor-Couette setup
A. Mishra, P. Personnettaz, G. Mamatsashvili, V. Galindo, F. Stefani. Physical Review Fluids 11, 014606 (2026). Published 26 January 2026. THEIA support acknowledged for P. Personnettaz; collaborative study of endcap effects in Taylor–Couette flow.

2025

Planetary dynamos driven by semi-convection in stratified layers
P. Pružina, D. Cébron, N. Schaeffer. Astronomy & Astrophysics 703, A135 (2025). Author manuscript / repository.

Modal acoustic velocimetry in libration-driven flows
H.-C. Nataf, S. Su, P. Roux, P. Cardin, D. Cébron, Y. Do. Experiments in Fluids 66 (10), 185 (2025). Author manuscript / repository. See also the publisher correction, Experiments in Fluids 66, 213 (2025) (not counted as a separate research article).

Topographic Drag at the Core-Mantle Interface
R. Monville, D. Cébron, D. Jault. Journal of Geophysical Research: Solid Earth 130 (4), e2024JB029770 (2025). Author manuscript / repository.

2024

Geophysical flows over topography, a playground for laboratory experiments
J. Vidal, J. Noir, D. Cébron, F. Burmann, R. Monville, V. Giraud, Y. Charles. Comptes Rendus. Physique 25 (S3), 183–234 (2024). Review. Author manuscript / repository. Volume year 2024; published online in 2025.

Compaction-Driven Convection in the Growing Inner Core
K. W. Lim, R. Deguen, D. Cébron, A. Schulze, M. Mandea. Geophysical Research Letters 51 (23), e2024GL110749 (2024). Author manuscript / repository.

Inertia-gravity waves in geophysical vortices
J. Vidal, Y. Colin de Verdière. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 480 (2285), 20230789 (2024).

2023

MHz free electron laser x-ray diffraction and modeling of pulsed laser heated diamond anvil cell
N. Jaisle, D. Cébron, Z. Konôpková, et al. Journal of Applied Physics 134 (9), 095904 (2023).

Precession-driven flows in stress-free ellipsoids
J. Vidal, D. Cébron. Journal of Fluid Mechanics 954, A5 (2023). Author manuscript / repository. First published online 23 December 2022.

2022

Sustaining Earth's magnetic dynamo
M. Landeau, A. Fournier, H.-C. Nataf, D. Cébron, N. Schaeffer. Nature Reviews Earth & Environment 3 (4), 255–269 (2022). Review.

Core Eigenmodes and their Impact on the Earth's Rotation
S. A. Triana, M. Dumberry, D. Cébron, J. Vidal, A. Trinh, F. Gerick, J. Rekier. Surveys in Geophysics 43 (1), 107–148 (2022). Review. First published online 10 November 2021.

2021

Acoustic modes of rapidly rotating ellipsoids subject to centrifugal gravity
J. Vidal, D. Cébron. Journal of the Acoustical Society of America 150 (2), 1467–1478 (2021). Author manuscript / repository.

Kinematic dynamos in triaxial ellipsoids
J. Vidal, D. Cébron. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477 (2252), 20210252 (2021). Author manuscript / repository.

The effects of a Robin boundary condition on thermal convection in a rotating spherical shell
T. T. Clarté, N. Schaeffer, S. Labrosse, J. Vidal. Journal of Fluid Mechanics 918, A36 (2021). Author manuscript / repository.

Mean zonal flows induced by weak mechanical forcings in rotating spheroids
D. Cébron, J. Vidal, N. Schaeffer, A. Borderies, A. Sauret. Journal of Fluid Mechanics 916, A39 (2021). Author manuscript / repository.

Earlier methodological foundation (before the ERC grant)

Acoustic and inertial modes in planetary-like rotating ellipsoids
J. Vidal, D. Cébron. Proceedings of the Royal Society A 476 (2239), 20200131 (2020). Published before the start of THEIA; included as a methodological precursor, not as an output funded by the ERC grant. Author manuscript.

The THEIA project received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 847433).

See the project homepage for the main scientific results and the Numerics page for the associated software.

ERC project THEIA

David CÉBRON, Jérémie VIDAL, Max SOLAZZO — 2022-02-09T07:47:35Z

Project	About Us	Publications	Communications	Numerics	Experiments	Gallery

THEIA team and collaborators, 2020–2026

David Cébron, CNRS researcher at ISTerre and principal investigator of ERC THEIA, led the project from September 2020 to August 2026. He built a group bringing together theory, numerical simulations and rotating-fluid experiments to investigate planetary core dynamics.

His collaborative research included ellipsoidal modes, forced flows and magnetic induction with Jérémie Vidal; topographic coupling with Rémy Monville and Dominique Jault; and semi-convective dynamos with Paul Pružina and Nathanaël Schaeffer. He also worked on inner-core coupling with Paolo Personnettaz and collaborators, and jointly conceived and designed the THEIA and mini-THEIA experiments with Max Solazzo.

Researchers

Rémy Monville — doctoral researcher, October 2020–March 2024; thesis defended on 22 April 2024, followed by further research contributions, including a short research-fellow appointment in October–November 2024. He developed ToCCo and the local theory of topographic coupling, working with David Cébron and Dominique Jault. Research and software.
Jérémie Vidal — research fellow, September 2020–January 2025. He developed and extended spectral methods for modes, forced flows, stability and magnetic induction in ellipsoidal cores, and subsequently became a permanent CNRS researcher. His numerical tools include SHINE, alongside the earlier SWAN and SIREN methods. Research and tools.
Paul Pružina — research fellow, October 2024–September 2025. With Nathanaël Schaeffer and David Cébron, he studied semi-convection, layered flows and dynamo generation in rotating stratified shells. The resulting publications also received subsequent collaborative support, including ChEESE-2P.
Paolo Personnettaz — contributor from December 2022, initially through complementary funding, with a project-team appointment from February 2025 to January 2026. He worked on XSHELLS developments and magnetohydrodynamic coupling, including inner-core translation and oscillating-sphere drag, with David Cébron, Nathanaël Schaeffer and collaborators. This work also involved ERC GRACEFUL.
Baptiste Penlou — THEIA postdoctoral researcher, September 2025–August 2026. He developed PIV acquisition and analysis methods and spin-up protocols using the intermediate tank, providing the basis for comparisons between smooth and rough bottoms.
Samuel Payen — doctoral researcher contributing to the experimental programme, January–April 2025.

Experimental engineering: design, construction and assembly

Max Solazzo, permanent CNRS engineer at ISTerre, jointly conceived and designed the THEIA and mini-THEIA experiments with David Cébron. He carried out their computer-aided design (CAD), mechanical construction and assembly.

The programme used mini-THEIA, approximately 50 cm across, and an intermediate tank approximately one metre across on the WEBER rotating platform. These devices supported the development of experimental procedures and the study of rotating flows over smooth and rough bottoms.

The Experiments page explains how the apparatus was used. The Gallery shows the assembled experiments, laser illumination and mechanical design. PIV acquisition, analysis and spin-up protocols were developed by Baptiste Penlou, following earlier experimental contributions including Samuel Payen's work.

Scientific collaborations

ISTerre collaborators included Dominique Jault for topographic-coupling theory and doctoral supervision, Nathanaël Schaeffer for XSHELLS and rotating-fluid and dynamo simulations, Renaud Deguen for inner-core dynamics, and Henri-Claude Nataf for rotating-fluid experiments and acoustic diagnostics.

Collaborative publications also involved Jérôme Noir and Vadim Giraud at ETH Zürich, Yves Colin de Verdière in mathematical wave theory, Mioara Mandea in inner-core and magnetic studies, and the co-authors credited in the individual papers.

Other students and interns also contributed to THEIA. The Publications page provides the full scientific references and authorship, and the project homepage presents the main scientific results.