Engineer F/H: Implementation of the coupling between magnetic effects and oscillations in code Hawen

We offer a one-year Research Engineer position within the Inria Makutu team at the University of Pau. The successful candidate will develop a computational framework to model the interaction between magnetic fields and wave oscillations in Hawen, an HPC code dedicated to wave propagation and inversion. The work will involve implementing, validating, and documenting new numerical developments, with a strong emphasis on robustness, performance, and scalability on modern high-performance computing (HPC) systems. In addition, automated pipelines will be developed to create synthetic observables from the code outputs.

In this project we focus on applications to helioseismology: the Sun is composed of plasma and is modeled mathematically as a continuous electrically conducting fluid governed by the equations of magnetohydrodynamics. Applying perturbation theory and linearization to these equations yields a system describing solar oscillations in the simultaneous presence of magnetic fields, gravity, rotation, and flows. The code currently ignores the magnetic field, and its incorporation constitutes a key ingredient in understanding solar dynamo which attempts to explain the generation and transport of the magnetic field in the Sun. On a local scale, the same set of equations can be employed to model local interaction of magnetic field with acoustic waves, for instance in active regions. This has direct application in helioseismic holography for far-side imaging of the Sun, which is of great important in space-weather forecast.

The objective of this project is to incorporate magnetic effects into the existing wave propagation code Hawen, which currently models wave oscillations in a variety of media. This extension will require implementing the linear induction equation and coupling it with the linear equation of motion already available in the code.

The project will begin with a familiarization phase, during which the successful candidate will gain an understanding of the team's computational framework and numerical methods. They will then develop and implement the appropriate numerical strategy, validate the implementation through representative benchmark problems, and document the new developments. In the final stage of the project, the code will be used to investigate the influence of magnetic fields on solar oscillations by comparing numerical predictions with observational data. The provisional schedule is as follows:

1. Familiarization with numerical framework in Hawen (structure of the benchmarks, code parallelism, I/O), the discretization method used in the code, and the existing solar oscillation equations currently available.

2. Implement an initial strategy which consists in a zero-th order term to add in the system of equations. Indeed, when ignoring the perturbation in magnetic field, the contribution of the Lorentz force in the equation of motion can be included as a zero-th order term, which avoid an increase in the number of unknowns. This step will help the successful candidate to familiarize with the code structure.

3. Implement the full coupling between the induction equation and the oscillation equation, and compare with the strategy developed in step 2.

4. Develop automated Python routines to post-process Hawen simulations into helioseismic observables (such as power spectrum, cross-covariance), enabling a quantitative investigation of the impact of considering the magnetic field. This step also includes a familiarization with observables and data processing performed in existing Python routines to process Dopplergrams to helioseismic observable.

The successful candidate is expected to develop and implement the numerical methodology, and document progress regularly through clear and detailed technical reports. The software developments will follow standard best practices, including version control, automated testing, verification and validation, comprehensive documentation, and code review. Particular attention will be devoted to ensuring numerical accuracy and scalability on modern high-performance computing (HPC) architectures.

The successful candidate will also develop automated workflows for data processing and post-processing, facilitating reproducible numerical experiments and comparisons with helioseismic observations. The progress will be documented through detailed technical reports and user guides, to contribute to the long-term sustainability of the software. As part of the Makutu team, the candidate will also be involved in all activities of the research team, through regular interactions with researchers, engineers, and students.

• Subsidized meals
• Partial reimbursement of public transport costs
• Possibility of teleworking and flexible organization of working hours
• Professional equipment available (videoconferencing, loan of computer equipment, etc.)
• Social, cultural and sports events and activities
• Access to vocational training
• Social security coverage

Between €2,692 and €2,765 gross per month (before taxs), depending on experience