Ecfd:ecfd 9th edition - Revision history

Mendez at 11:48, 26 February 2026

2026-02-26T11:48:17Z

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

2026-02-16T10:02:14Z

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

Merlin at 10:42, 12 February 2026

2026-02-12T10:42:03Z

Thomas.laroche: /* TP3 - Modeling of a gear wheel immersed in an oil bath */

2026-02-10T15:58:25Z

‎TP3 - Modeling of a gear wheel immersed in an oil bath

Meynet: /* TP1 - Simulation of core shifting during investment casting - Y. Mayi (Safran), M. Cailler (Safran), S. Meynet (GDTech) */

2026-02-10T09:31:44Z

‎TP1 - Simulation of core shifting during investment casting - Y. Mayi (Safran), M. Cailler (Safran), S. Meynet (GDTech)

Ybechane at 09:28, 10 February 2026

2026-02-10T09:28:22Z

Ybechane at 09:23, 10 February 2026

2026-02-10T09:23:08Z

Balarac: /* Mesh adaptation - A. Grenouilloux (ONERA) & G. Balarac (LEGI) */

2026-02-09T20:12:29Z

‎Mesh adaptation - A. Grenouilloux (ONERA) & G. Balarac (LEGI)

Agrenouilloux: /* M6 – Static mesh adaptation workflow based on on-the-fly computed metrics - Q. Douasbin (CERFACS), A. Pestre(CERFACS), P. Picard(CERFACS), L. Carbajal-Carrasco (Safran) & T. Duranton(Safran) */

2026-02-09T12:48:47Z

‎M6 – Static mesh adaptation workflow based on on-the-fly computed metrics - Q. Douasbin (CERFACS), A. Pestre(CERFACS), P. Picard(CERFACS), L. Carbajal-Carrasco (Safran) & T. Duranton(Safran)

Agrenouilloux: /* Mesh adaptation - A. Grenouilloux (ONERA) & G. Balarac (LEGI) */

2026-02-09T12:46:34Z

‎Mesh adaptation - A. Grenouilloux (ONERA) & G. Balarac (LEGI)

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 === Hackathon GENCI - P. Begou (LEGI), V. Moureau (CORIA) ===
 This ECFD9 GENCI Hackathon was a rich event, involving 3 differents CFD codes (AVBP, SONICS and YALES2) using various paradigms (C++/cuda/hip, Fortran/OpenMP/OpenACC) with several SDKs (AMD, Cray/HPE, Nvidia, Gnu) on a large range of GPU architectures (Nvidia A100, GH100, AMD instinct Mi210, Mi250, Mi300). This two-week event benefited from a high level support from three HPC mentors, two on-site from AMD (J. Noudohouenou and A. Tsetoglou).
 ==== H3 - Hackathon SONICS - A. de Brauer (ONERA),  B. Michel (ONERA),  B. Berthoul (ONERA) & G. Staffelbach (ONERA) ====

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 Shock waves were detected with a Jameson-type pressure-based sensor, while contact discontinuities were identified with a temperature-based sensor. The pressure-based sensor was scaled to obtain a kinematic viscosity contribution, which was incorporated into the LBM collision relaxation time. Similarly, the temperature-based sensor was scaled to define an artificial thermal conductivity, which was added to the FV discretization of the total energy equation.
 A set of validation cases—including the Sod shock tube at various pressure ratios, a 2D Riemann problem, and the interaction of a shock wave with a helium bubble in air—was performed. The results demonstrate that the hybrid LBM approach is capable of accurately capturing shocks and contact discontinuities, even on relatively coarse meshes, while avoiding spurious Gibbs oscillations.
 ==== N5 - Dorothy: Toward Fully Distributed Implementation - A. Vergnaud (LOMC), M. Roperch (LOMC) & G. Pinon (LOMC) ====

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 Simulating jet-in-crossflow (JICF) configurations using LES for industrial applications is complex due to the high computational cost associated with fully resolving jets, especially for computations in reactive conditions. Within a purely Lagrangian approach, certain physical phenomena—such as surface or column break-up—are not effectively captured. This project aims to assess the Lucid model (Charles et al., International Conference on Numerical Combustion, 2025), which introduces a liquid column representation into the Lagrangian framework, by comparing its performance against a fully resolved SPS simulation of a JICF case validated by experimental data. Additionally, a pure Lagrangian injection case, namely without any ad-hoc model for the jet, is also analyzed. The results indicate that the Lucid model better captures surface breakup dynamics when compared to the pure Lagrangian approach. Nevertheless, both Lagrangian-based methods overlook aerodynamic blockage effects of the liquid column, potentially influencing the downstream distribution of droplets.
-==== TP7 - Validation and extension of PCS solver for cryo tanks ====
+==== TP7 - Validation and extension of PCS solver for cryo tanks, C. Merlin (AGS), V. Moureau (CORIA), T. Laurent (CORIA/AGS), D. Fouquet (CORIA), J. Carmona (CORIA) ====
 ==== TP8 - Jet-in-crossflow simulation with the Hybrid SPH-FVM solver - M. Helal (CORIA/Safran), M. Cailler (Safran), V. Moureau (CORIA) ====

← Older revision		Revision as of 15:58, 10 February 2026
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	==== TP3 - Modeling of a gear wheel immersed in an oil bath ====		==== TP3 - Modeling of a gear wheel immersed in an oil bath ====
		+
		+	The main objective of this project was to model the rotation of a gear wheel immersed in an oil bath using YALES2. Such a phenomenon occurs in aeronautical power transmission systems, either intentionally for the lubrication of solid contacts, or unintentionally, leading to gulping effects that may critically impact aircraft performance. The ECAM configuration serves as a well-studied, simplified representation of scenarios encountered within engines; it provides diagnostics on both oil projection quantities and the torque exerted by the oil on the gear.
		+	During ECFD9, the necessary components to enable the modelling of this phenomenon were established, thus allowing computation for this configuration. The coupling between the ALE and SPS solvers was adapted to the numerical schemes recommended for two-phase flow simulations, allowing initial iterations on the final setup. Nevertheless, modelling the contact point at the liquid–gas–solid interface remains a challenge to ensure numerical stability, and will be addressed in future work.

	==== TP4 - Implementation of a granular temperature model - T. Ndereyimana (Université de Sherbrooke), S. Moreau (Université de Sherbrooke), Y. Dufresne (Enerkem) ====		==== TP4 - Implementation of a granular temperature model - T. Ndereyimana (Université de Sherbrooke), S. Moreau (Université de Sherbrooke), Y. Dufresne (Enerkem) ====

← Older revision		Revision as of 09:31, 10 February 2026
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	==== TP1 - Simulation of core shifting during investment casting - Y. Mayi (Safran), M. Cailler (Safran), S. Meynet (GDTech) ====		==== TP1 - Simulation of core shifting during investment casting - Y. Mayi (Safran), M. Cailler (Safran), S. Meynet (GDTech) ====
		+
		+	Ceramic core displacement and deformation during the casting process is a major source of cooled blades manufacturing scrap. Predictive numerical simulations of the casting process would be an essential asset to increase the efficiency of the conception and industrial processes. At ECFD7, the numerical setup to simulate the filling process with YALES2 was drawn and results were compared to simplified casting experiment on a test blade. And at ECFD8, the deformation of the test blade was addressed via a numerical chaining between YALES2 and ABAQUS (FEM software). During this ECFD9 workshop, two objectives were targeted: 1) study the impact of different physics (contact angles, partial vacuum) on the fluidic forces exerted on the core 2) linked to the TP3 project, challenge a new SPS-ALE solver in YALES2 concerning the shifting of the core. About the first objective, several simulations have been conducted on a test case and on an industrial configuration. The first results showed that it was important to take surface tension and contact angles into account with regard to force amplitudes. Partial vacuum also has an influence. However, the force curves show a similar trend to those obtained without these different models, and the cost of the simulation is lower. It is therefore necessary to find a compromise between the best possible accuracy and the cost for future simulations. Concerning the second objective, test simulations have highlighted the need of debugging / cleaning sessions for the SPS-ALE solver. The later have been done by Mélody Cailler and Vincent Moureau and have led to a functional solver. This work paves the way for accurate two-phase flows and moving bodies simulations with YALES2.

	==== TP2 - Lattice Boltzmann method for free-surface two-phase flow - J. Lu (M2P2), Y. Mediene (M2P2), I. Tsetoglou (M2P2) & S. Zhao (M2P2) ====		==== TP2 - Lattice Boltzmann method for free-surface two-phase flow - J. Lu (M2P2), Y. Mediene (M2P2), I. Tsetoglou (M2P2) & S. Zhao (M2P2) ====

← Older revision		Revision as of 09:28, 10 February 2026
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	Integration of chemical source terms remains computationally expensive in configurations that rely on detailed chemistry approach. This project aimed to reduce that cost by (1) modifying the CVODE integration strategy and (2) applying source-term clustering. A first attempt was to modify CVODE’s internal step-size control strategy but it produced only minor gains as some unnecessary integration steps still occurred, mainly in the unburned gases region. This has finally been addressed by enforcing an initial step based on the CFD time step which reduced the computational cost by a factor 2 in these regions. More importantly, relaxing the relative and absolute tolerances used to determine the accuracy of the method reduced the computational cost by approximately 40% while introducing negligible error in physical properties and flame topology for a 1D premixed flame. These results were confirmed on three methane flame configurations: a 1D premixed flame, a 2D triple flame, and the PRECCINSTA burner. Numerical experiments on the PRECCINSTA burner show a reduction in integration cost by a factor of 2.5 using the adjusted CVODE strategy and by a factor of 4.4 when that strategy is combined with clustering.		Integration of chemical source terms remains computationally expensive in configurations that rely on detailed chemistry approach. This project aimed to reduce that cost by (1) modifying the CVODE integration strategy and (2) applying source-term clustering. A first attempt was to modify CVODE’s internal step-size control strategy but it produced only minor gains as some unnecessary integration steps still occurred, mainly in the unburned gases region. This has finally been addressed by enforcing an initial step based on the CFD time step which reduced the computational cost by a factor 2 in these regions. More importantly, relaxing the relative and absolute tolerances used to determine the accuracy of the method reduced the computational cost by approximately 40% while introducing negligible error in physical properties and flame topology for a 1D premixed flame. These results were confirmed on three methane flame configurations: a 1D premixed flame, a 2D triple flame, and the PRECCINSTA burner. Numerical experiments on the PRECCINSTA burner show a reduction in integration cost by a factor of 2.5 using the adjusted CVODE strategy and by a factor of 4.4 when that strategy is combined with clustering.
		+
		+	==== C10 – Anisotropic mesh adaptation for reacting flows- N. Moslimani (CORIA), R. Barbera (LEGI), K. Bioche (CORIA), G. Lartigue (CORIA) ====
		+
		+	Anisotropic mesh adaptation (AMA) with high aspect ratios has been shown in multiphase-flow simulations to reduce accuracy in regions of high interface curvature, motivating the use of locally isotropic meshes. This work investigated whether a similar limitation arises in combustion simulations with curved flame fronts when using a level-set–based AMA strategy. A two-dimensional planar premixed flame subjected to inlet mixture inhomogeneities was considered, leading to flame wrinkling and localized regions of high curvature. A sensitivity study with respect to the imposed aspect ratio was performed, comparing isotropic adaptation with anisotropic adaptation at increasing aspect ratios. All configurations yielded nearly identical flame shapes and accurately resolved curvature, showing no reduction of solution quality with increasing anisotropy. This indicates that varying the aspect ratio as a function of curvature is not necessary for combustion applications. However, the distance-based remeshing criterion used in level-set–based AMA was found to delay adaptation during rapid flame tilting, leading to temporary misalignment between anisotropic cells and the flame front. To address this issue, a new remeshing criterion based on local metric comparison was introduced, triggering adaptation whenever the desired flame-aligned metric is not included in the expanded actual mesh metric within a narrow band around the flame, ensuring robust alignment and resolution during flame reorientation.

	==== C11 - Optimization of decoupled approach for heat transfers - T.-P. Luu (GDTech), R. Letournel (Safran), M. Tripiciano (Safran) ====		==== C11 - Optimization of decoupled approach for heat transfers - T.-P. Luu (GDTech), R. Letournel (Safran), M. Tripiciano (Safran) ====

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 A virtual chemistry framework yielding global-type mechanisms has recently been developed and validated, allowing accurate prediction of flame structures at a substantially reduced computational cost. By coupling virtual chemistry with Adaptive Mesh Refinement (AMR) strategies, this work assesses the ability to dynamically resolve reactive zones while maintaining affordable computational costs in high-fidelity LES of industrial burners. A second objective of ECFD9 was to disseminate the virtual schemes generated using SuperVision, a Python-based automated optimization tool built on Cantera. An optimized hydrogen virtual mechanism was successfully implemented and validated in the Lattice–Boltzmann solver ProLB, demonstrating the ease with which these standardized schemes can be integrated into existing reactive flow solvers, and the spread potential of this new chemistry reduction strategy in the combustion community. Finally, the NOx virtual submechanism for hydrogen combustion was improved to accurately capture both thermal and prompt NO formation in hydrogen flames.
-==== C7 - TEMPERATURE BOUNDARY CONDITIONS FOR TABULATED CHEMISTRY - P. Illu,inqti (EM2C), R. Vicquelin (EM2C ====
+==== C7 - Temperature boundary conditions for tabulated chemistry - P. Illuminati (EM2C), R. Vicquelin (EM2C ====
 Tabulated chemistry workframe usually rely on transporting an Enthalpy scalar to account for Heat Losses, resulting in tables that have a few dimension for the thermochemical state (e.g. Z, YC, etc) and a transported scalar for generic heat losses (e.g. ENTHALPY). In order to generalize the use of tabulated chemistry models for Heat Losses (Conjugate Heat Transfer, Radiation Heat Losses etc...) a new Boundary Condition has been developed that will allow the user to impose a tempearture on the wall and to retrieve accordingly the transported ENTHALPY value that enforces such condition. The boundary condition is available in the VDS solver, when the scalar of type ENTHALPY is being imposed. (to be merged)

@@ Line 194: / Line 194: @@
 === Mesh adaptation - A. Grenouilloux (ONERA) & G. Balarac (LEGI) ===
 ==== M2 – Dynamic of SWBLI in Supersonic Propulsive Nozzle Under Hot Gas Conditions - F.A. Rojas Segovia (CORIA), Y. Bechane (CORIA) & L. Voivenel (CORIA) ====
 In this project, a STBLE (Solution Thin Boundary Layer Equations) wall model was implemented in YALES2. The focus was to add and compare this model with the pre-existing wall models in the code, such as the logarithmic law and Duprat, in the context of supersonic nozzles. To achieve this, 2D simulations of supersonic compressible flow over a flat plate were conducted as an initial step and validation. These initial simulations provided good insights for future research on the dynamics of Shock Wave and Boundary Layer Interaction (SWBLI) in supersonic nozzles operating with both cold and hot gas conditions.

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 This project investigates anisotropic mesh adaptation strategies for multiphase flows, with the objective of reducing computational cost while preserving an accurate representation of fluid interfaces. The approach relies on curvature-based anisotropic remeshing, where mesh anisotropy is locally controlled from interface geometry to ensure a prescribed discretization angle. A key limitation of anisotropic coarsening along interfaces is mass loss induced by interpolation during remeshing, which increases with tangential coarsening and therefore directly conflicts with anisotropic strategies. During ECFD9, this issue was addressed by introducing a high-order interpolation scheme for interface variables, replacing the default linear interpolation. The results show that high-order interpolation significantly reduces mass loss, allowing for much higher mesh anisotropy at the interface, at the cost of a limited computational overhead. In addition, the curvature-based adaptation strategy was extended from mean curvature to the full curvature tensor, enabling the mesh to align with the two principal curvatures of three-dimensional interfaces. The approach was demonstrated on canonical multiphase configurations, including droplet advection and rising bubble cases, showing substantial reductions in mesh size compared to isotropic simulations. Ongoing perspectives include coupling curvature-based adaptation with feature-based anisotropic remeshing to better capture turbulent structures away from the interface.
-==== M6 – Static mesh adaptation workflow based on on-the-fly computed metrics - Q. Douasbin (CERFACS), A. Pestre(CERFACS), P. Picard(CERFACS), L. Carbajal-Carrasco (Safran) & T. Duranton(Safran) ====
+==== M6 – Static mesh adaptation workflow based on on-the-fly computed metrics - Q. Douasbin (CERFACS), A. Pestre(CERFACS), P. Picard(CERFACS), L. Carbajal-Carrasco (Safran) & T. Duranton (Safran) ====
 Reactive Large Eddy Simulations (LES) for industrial applications are computationally expensive, and mesh adaptation represents an effective strategy to reduce this cost while preserving solution accuracy. The current Adaptative Static Mesh Refinement (ASMR) workflow suffers from 1) a history effect that keeps cells in regions previously refined and 2) a global cell size constraint that prevents fine control of the local cell size.

← Older revision		Revision as of 12:46, 9 February 2026
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	This project investigates anisotropic mesh adaptation strategies for multiphase flows, with the objective of reducing computational cost while preserving an accurate representation of fluid interfaces. The approach relies on curvature-based anisotropic remeshing, where mesh anisotropy is locally controlled from interface geometry to ensure a prescribed discretization angle. A key limitation of anisotropic coarsening along interfaces is mass loss induced by interpolation during remeshing, which increases with tangential coarsening and therefore directly conflicts with anisotropic strategies. During ECFD9, this issue was addressed by introducing a high-order interpolation scheme for interface variables, replacing the default linear interpolation. The results show that high-order interpolation significantly reduces mass loss, allowing for much higher mesh anisotropy at the interface, at the cost of a limited computational overhead. In addition, the curvature-based adaptation strategy was extended from mean curvature to the full curvature tensor, enabling the mesh to align with the two principal curvatures of three-dimensional interfaces. The approach was demonstrated on canonical multiphase configurations, including droplet advection and rising bubble cases, showing substantial reductions in mesh size compared to isotropic simulations. Ongoing perspectives include coupling curvature-based adaptation with feature-based anisotropic remeshing to better capture turbulent structures away from the interface.		This project investigates anisotropic mesh adaptation strategies for multiphase flows, with the objective of reducing computational cost while preserving an accurate representation of fluid interfaces. The approach relies on curvature-based anisotropic remeshing, where mesh anisotropy is locally controlled from interface geometry to ensure a prescribed discretization angle. A key limitation of anisotropic coarsening along interfaces is mass loss induced by interpolation during remeshing, which increases with tangential coarsening and therefore directly conflicts with anisotropic strategies. During ECFD9, this issue was addressed by introducing a high-order interpolation scheme for interface variables, replacing the default linear interpolation. The results show that high-order interpolation significantly reduces mass loss, allowing for much higher mesh anisotropy at the interface, at the cost of a limited computational overhead. In addition, the curvature-based adaptation strategy was extended from mean curvature to the full curvature tensor, enabling the mesh to align with the two principal curvatures of three-dimensional interfaces. The approach was demonstrated on canonical multiphase configurations, including droplet advection and rising bubble cases, showing substantial reductions in mesh size compared to isotropic simulations. Ongoing perspectives include coupling curvature-based adaptation with feature-based anisotropic remeshing to better capture turbulent structures away from the interface.
		+
		+	==== M6 – Static mesh adaptation workflow based on on-the-fly computed metrics - Q. Douasbin (CERFACS), A. Pestre(CERFACS), P. Picard(CERFACS), L. Carbajal-Carrasco (Safran) & T. Duranton(Safran) ====
		+
		+	Reactive Large Eddy Simulations (LES) for industrial applications are computationally expensive, and mesh adaptation represents an effective strategy to reduce this cost while preserving solution accuracy. The current Adaptative Static Mesh Refinement (ASMR) workflow suffers from 1) a history effect that keeps cells in regions previously refined and 2) a global cell size constraint that prevents fine control of the local cell size.
		+	The objective of this project is to address these limitations by developing a new workflow for AVBP driven by physics-based criteria and capable of performing each adaptation from the initial coarse mesh. In this context, the objectives of the project are twofold: 1) develop a new ASMR workflow and 2) define a target mesh for each Quantity of Interest.
		+	A prototype of a flexible ASMR workflow was developed to run multiple simulation scenarios. It is based on the Lemmings and Tekigo libraries, developed at CERFACS, to handle the orchestration of successive simulation jobs and the generation of the mesh adaptation process, respectively. Several phases of simulations, each composed of several stages, allow an efficient mesh convergence.
		+	For each physics of interest a target mesh is determined and the adapted local cell size is the smallest cell size of all metrics. The turbulent combustion mesh is based on the TFLES model and consists of a target flame thickening factor that takes into account the probability of flame presence. The pressure drop and turbulent flow mesh is based on the work of H. Lam and G. Balarac which defines the metric based on two criteria i) a cell Reynolds number for DNS. ii) When the Kolmogorov to integral length scale ratio is high enough in a cell, the flow is deemed suitable for LES and the cell size is fixed via a constant number of cells per local integral length scale. The implementation and validation of this second metric are currently ongoing.

	==== M7 – Increased mesh anisotropy for laminar and RANS applications - R. Barbera (LEGI), J.-B. Lagaert (LMO), T. Berthelon (LEGI), R. Letournel (Safran), M. Bernard (LEGI) & G. Balarac (LEGI) ====		==== M7 – Increased mesh anisotropy for laminar and RANS applications - R. Barbera (LEGI), J.-B. Lagaert (LMO), T. Berthelon (LEGI), R. Letournel (Safran), M. Bernard (LEGI) & G. Balarac (LEGI) ====