Revision as of 13:58, 2 February 2026

Description

• Event from 19th of January to 30th of January 2026
• Location: Centre Sportif de Normandie, Houlgate, near Caen (14)
• Two types of sessions:
  • common technical presentations: roadmaps, specific points
  • mini-workshops. Potential workshops are listed below
• Free of charge
• Participants from academics, HPC center/experts and industry are welcome
• The number of participants is limited to 80.

• Organizers
  • Guillaume Balarac (LEGI), Simon Mendez (IMAG), Pierre Bénard, Vincent Moureau, Léa Voivenel (CORIA).

News

• 22/09/2025: First announcement of the 9th Extreme CFD Workshop & Hackathon !
• 15/11/2025: Deadline to submit your project

Thematics / Mini-workshops

To be announced...

Projects

The projects will be selected after the end of the submission phase (end of November).

Numerics & User Interface - M. Bernard (LEGI), G. Lartigue (CORIA) & S. Mendez (IMAG)

N6 - Relaxation of the IBM stability constraint - PL. Martin (IMAG) & S. Mendez (IMAG)

Many simulations done in the YALES2BIO framework involve fluid-structure interactions handled with the Immersed Boundary Method (IBM). This model allows for the fluid/solid coupling, with the forces from the solid acting as a source term in the Navier-Stokes equations. In some cases for red blood cells simulations, and for most cases for von Willebrand Factor simulations, the governing time step is the force time step. When this is the case, we also notice artifacts in the fluid velocity and pressure fields. The robustness of our IBM implementation was improved for embedded surfaces by shifting our regularization/interpolation kernels away from the wall in case we work with an embedded solid. Since these simulations are done at low Reynolds and CFL number (0.01 - 0.001), the stability constraint was relaxed by doing substeps without: 1. advancing the convective velocity, 2. correcting the velocity to make it divergence-free. The artifacts showing when solids are a lot stiffer than the fluid viscous forces were reduced by projecting the regularized solid forces into a divergence-free space.

Turbulence - L. Voivenel (CORIA), P. Bénard, CORIA & T. Berthelon (LEGI)

T5 – Hybrid RANS/LES based on dual mesh and LES of fluctuations - G. Balarac (LEGI), T. Berthelon (LEGI) & R. Letournel (Safran)

This project is devoted to a fully coupled hybrid RANS/LES strategy based on a dual-mesh framework, where the mean flow is solved by RANS on a mesh tailored for the mean field, while only the turbulent fluctuations are resolved by LES on a second mesh. In addition to deterministic drift (relaxation) terms that drive the resolved velocities in each model toward target fields provided by the other one (RANS mean for LES, LES statistics for RANS), a stochastic forcing built from RANS turbulent quantities is introduced in the LES of fluctuations. These combined forcing terms allow a controlled generation of fluctuations at the RANS/LES interface and reduce the sensitivity to interface location. Two-way coupling is achieved by feeding back the Reynolds stresses computed in the LES into the RANS equations in the resolved regions. The approach is demonstrated on turbulent pipe flows, including a fully coupled simulation at high Reynolds number (Re = 44,000), showing that the method enables wall-resolved hybrid simulations at a fraction of the cost of a full LES.

T9 - LES-based aero-servo-elastic simulation of wind turbines - E. Muller (CORIA & SGRE), P. Benard (CORIA), F. Houtin-Mongrolle (SGRE), B. Duboc (SGRE) & H. Hamdani (GDTech)

The YALES2 library includes an advanced modular implementation of the Actuator Line Method (ALM). This approach remains state-of-the-art when performing an LES-based analysis of a wind turbine wake. The method also provides an accurate assessment of the aerodynamic loads applied on the turbine as well as the structural deformation when Yales2 is coupled to an external library/code. In the past years two coupling library have been developed, one to BHawC (SGRE certification tool) and one to OpenFast (NREL open access/open source). To improve the user and developer experience a generalization of the two coupling is conducted in this project.

WP1/2: Update the existing coupling libraries for OpenFast and BHawC coupling with ALM of YALES2.

WP3: Generalize/uniformalize the coupling DLL and the calls to it in YALES2.

WP4: Enable both coupling to work with both Actuator lines and Actuator Disks.

WP5: Implementation and integration of the Risoe Dynamic stall model. Following ECFD6 T5 (Turbulence flow project 5).

WP6: Miscellaneous related to actuator line covered through this ECFD9.

Combustion - Y. Bechane (CORIA), R. Letournel (Safran) & S. Dillon (Safran)

C8 - Optimization of chemical source terms stiff integration - Y. Bechane (CORIA), G. Lartigue (CORIA), K. Bioche (CORIA), Q. Cerutt (CORIAi, M. El Moatamid (CORIA) & M. Laignel (CORIA)