Engineering Internship – System/CFD Co-simulation: an FMI Thermal Component Library for code_saturne

Engineering Internship – System/CFD Co-simulation: an FMI Thermal Component Library for code_saturne

Internship, 6 months. Coupling 0D/1D thermal equipment models (Modelica, FMU) with code_saturne CFD simulations.

Context

Simvia, a subsidiary of the EDF Group, is a key player in promoting and supporting open-source numerical simulation solutions, including code_saturne. Numerical simulation of fluid flows and heat transfer is an essential tool for studying the energy performance and thermal behaviour of buildings, industrial facilities and data centres. Computational fluid dynamics (CFD) software, such as the open-source solver code_saturne, can accurately represent airflows, convection phenomena and the spatial distribution of temperature. However, representing thermal equipment (radiators, air conditioners, fans, server racks, CRAC/CRAH units, etc.) usually requires defining boundary conditions and source terms, and in some cases developing dedicated user functions. At the same time, many 0D/1D model libraries, notably Modelica Buildings, BuildSysPro and ThermoSysPro, provide dynamic models of thermal and thermohydraulic components that include their physical characteristics, inertia and control systems. The Functional Mock-up Interface (FMI) standard makes it possible to package these models as Functional Mock-up Units (FMUs) and to couple them with other simulation tools.

The goal of this internship is to explore an approach for reusing these models to build a library of configurable physical components that can be integrated into CFD simulations run with code_saturne.

Practical information

• Contract type: end-of-studies internship (internship agreement required)
• Duration: 4 to 6 months
• Start: January 2027 (exact start date to be agreed)
• Location: EDF Lab, Saclay campus (Palaiseau, France)
• Compensation: in accordance with current regulations

Working environment

You will join a small, close-knit and passionate team based at EDF Lab on the Paris-Saclay campus, one of the most stimulating research and innovation ecosystems in Europe.

We genuinely care about our team's well-being: a supportive atmosphere, open communication, everyday mutual help and the right to make mistakes.

The role

The internship aims to study, develop and validate a software architecture that links dynamic thermal equipment models to geometric zones and to physical quantities computed by code_saturne.

Ultimately, a user could, for example, define a radiator with a nominal power of 1,000 W, assign it a setpoint temperature of 20 °C and place a virtual thermostat in a room. The coupling system would then automatically exchange temperatures and heat flows between the radiator model and the CFD computation. The intended approach should allow equipment models to be reused without writing new user routines for each component.

The work will be organised in four steps:

1. Literature review and analysis of existing solutions

Study coupling architectures between 0D/1D models and 3D CFD. Analyse the existing FMI features in code_saturne, in particular its FMU export interface. Identify suitable thermal models in the available Modelica libraries.

2. Design of a generic coupling architecture

Define an architecture for linking FMU models to zones and sensors in a CFD simulation. Define the time synchronisation mechanisms between the system models and the CFD solver. Propose a configuration format for declaring and parameterising equipment independently of the solver code.

3. Development of a first demonstrator: thermostatic radiator

Develop a demonstrator of thermal control in a code_saturne CFD computation, based on a Modelica radiator model coupled through FMI.

4. Numerical verification and coupling analysis

Check the physical and numerical consistency of the coupling, in particular energy balances and the influence of the communication step size. Assess whether the approach can be extended to other equipment (fans, air conditioners, server racks, etc.). A comparison with a control loop implemented directly in code_saturne user functions may also be carried out.

Who we're looking for

Second-year Master's (M2) or final-year engineering school student, specialising in fluid mechanics, heat transfer or numerical simulation.

Technical skills:

• Good knowledge of fluid mechanics and heat transfer
• Programming in Python and/or C/C++
• Interest in developing scientific simulation tools

Soft skills:

• Proactive: you enjoy going beyond your initial objectives
• Curious: you like understanding how things work
• Independent: you can manage your own priorities and make progress without constant guidance

What we offer

• Work on open-source tools from the EDF ecosystem: code_saturne and ThermoSysPro
• Concrete applications: buildings, industrial facilities, data centres
• Supervision by an experienced, available and passionate team

The position

• Engineering
• Palaiseau
• Full-time
• 1200 - 1500€ mensuel
• Internship

Apply by email, with the job title as subject.