add abstract 2025

Author: frederichecht

2022/pdf/edp-c/composite_contact_thermique.edp

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+##  Numerical simulation of a 3d regularized Boussinesq system 
+## Leila Azem      [email protected]
+
+## Faculty of sciences Tunis Manar
+
+
+*Abstract:*Abstract : We investigate in this work a numerical study of a 3d regularized Boussinesq system. In particular, we establish numerical results of convergence and existence as the regularization parameter vanishes

2025/md/AL.md

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+## FreeFem-CS
+## Dr A. le Hyaric   [email protected]
+
+## CNRS/ LJLL / Sorbonne universote 
+
+
+*Abstract:*  FreeFEM-cs is an integrated environment for FreeFEM. It provides an intuitive graphical interface with a color-coded editor where undefined variables are highlighted in red, a compilation window which links back to the source code, and integrated 3D graphics. This talk will describe how FreeFEM-cs can be used to experiment with the finite element method after one single download. https://www.ljll.fr/lehyaric/ffcs
+

2025/md/ALH.md

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+## An inverse problem to determine volcanic structure and its eigenvalue analysis in higher precision
+## Dr A. Suzuki   [email protected]
+
+## D3 Center, The University of Osaka / RIKEN Center for Computational Science
+
+
+*Abstract:*  We would like to determine stress distribution on the magma reservoir under the volcano from the surface displacement. The first step for the simulation is to construct an inverse problem by fixing the shape and depth of the magma reservoir and by assuming kinematic balance of the linear elasticity. The problem is described as a determination process of the stress on the internal boundary under given surface displacement to attain zero stress on the surface boundary. This setting is formulated as a variational problem, but discretization returns over/under-determined system depending on the degrees of freedom of the internal reservoir and surface boundaries. The other formulation is based on the minimization process of a cost function to evaluate difference between surface displacement calculated from the linear elasticity problem with controlling stress data and observed displacement. By applying the adjoint method, a variational formulation of the stress on the internal boundary is obtained and the adjoint solution is expressed as a harmonic extension from the surface displacement of the state solution. The discretized system is symmetric and positive semi-definite, but is not easy to solve numerically. Characteristics of the linear system is expressed as a generalized eigenvalue problem and the Lanczos process in higher precision helps us to understand how the problem is ill-conditioned. We will show FreeFEM code for three-dimensional problem by specifying indexing of internal and surface boundary nodes and linear operator by state and adjoint solutions.

2025/md/AS.md

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+## Numerical study of sapflow measurement in vegetal combining microwave heat pulse and thermal imaging (TIMFLOW method)
+## Christophe Coillot    [email protected]
+
+## University de montpellier / CNRS 
+
+
+*Abstract:* Numerical study of sapflow measurement in vegetal combining microwave heat pulse and thermal imaging (TIMFLOW method) (authors : C. Coillot, L. Faye, H.. Louche, A. Penarier, P. Nouvel, B. Clair, F. Do.) Sapflow measurment in tree and plants gives informations about their health in their environment. This knowledge is especially relevant in the context of the climate change where the thermal and hydric stresses are more and more pregnant. In this aim we have developed a sapflow method measurment combining microwave heat pulse and infrared thermal imaging. (TIMFLOW method). To investigate the response of the TIMFLOW method in a more quantitative way and explore its potential and limits we have modeled TIMFLOW method using freefem. In this presentation we will describe the physical model implemented and the parameters of the simulation. The 2D simulation results and the link with experimental datas will be discussed. We will conclude wiith the status of the 3D simulation aiming to approach more realistic conditions.

2025/md/CC.md

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+## Hemodynamic Modeling of Cerebral Aneurysms: Coupling 4D Flow MRI and Finite Element Simulations
+## Ms Esther Fontaine  [email protected]
+
+## LMR -- UMR9008 -- Université de Reims Champagne-Ardenne
+
+
+*Abstract:*  Abstract: Cerebral aneurysms, i.e. localized dilations of the arterial wall, pose a critical clinical challenge due to their potential to rupture, causing subarachnoid hemorrhages and severe ischemic complications. This work aimed to improve the prediction of cerebral aneurysms evolution by integrating Magnetic Resonance Imaging (MRI) into Computational Fluid Dynamics (CFD), based on the finite element method in FreeFEM++. To validate this MRI-to-CFD pipeline, a vascular phantom was employed. Anatomical and velocity data were extracted from 4D Flow MRI sequences to reconstruct vessel geometry and quantify blood flow. The vessel geometries were subsequently meshed, and fluid simulations were performed and compared with MRI velocity fields to refine the computational model. Numerical simulations were performed using the steady dimensionless Stokes equations on high-resolution meshes, requiring parallel implementation for computational efficiency. The resulting 3D flow fields, obtained from models with and without aneurysms, will be presented and analyzed, along with derived hemodynamic markers relevant to aneurysm evolution.

2025/md/EF.md

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+## An Artificial Neural Network for Predicting the Roles of Contacting Bodies in Computational Contact Mechanics 
+## Dr Houssam Houssein    [email protected]
+
+## Airthium 
+
+
+*Abstract:* The resolution of mechanical contact between two bodies using numerical methods, such as the finite element method (FEM), requires the prior assignment of contacting roles--slave or master--to each body, which is performed before solving the contact problem. When a body is designated as the slave, non-penetration constraints are imposed to prevent penetration into the master. To ensure accurate results, each body must be assigned the correct role, a task that is complex and often impractical to perform manually. To address this, artificial neural networks (ANNs) are proposed in this presentation for three 2D mechanical contact problems to automatically assign the appropriate roles, thereby improving accuracy while reducing computational cost compared to the symmetric formulation, where no role assignment is required. A data generation strategy, essential for training the ANNs and implemented using FreeFEM, is also presented.

2025/md/HH.md

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+## Towards multi-scale topology optimisation of microchannel cooling 
+## Dr Hao Li   [email protected]
+
+## University of Southern Denmark
+
+
+*Abstract:* Towards multi-scale topology optimisation of microchannel cooling. Efficient thermal management is a critical challenge in high-power-density electronics and heat exchangers. This talk presents our recent developments on multi-scale topology optimisation (TO) of microchannel cooling, leveraging FreeFEM for coupled thermal-fluid simulations and optimisation. In the first part, we employ a homogenisation-based multi-scale TO framework that couples macroscopic conjugate heat transfer problem with parameterised microscopic unit-cell simulations. The homogenised permeability and conductivity tensors are pre-computed to construct an offline library. With gradient-based optimiser, the microstructures parameters are fine-tuned, and de-homogenisation procedure reconstructs manufacturable microchannel geometries. In the second part, we rely on a brute-force density-based TO approach using a reduced-dimensional conjugate heat transfer model. Particular attention is given to the efficient solution of the adjoint problem by exploiting PETSc functionality, which enables memory- and time-efficient computation of sensitivities without explicitly assembling the transposed Jacobian. Both approaches are implemented within the FreeFEM ecosystem, combining its PETSc interface for scalable linear algebra operations, block-matrix formulations, and custom adjoint sensitivity analyses. The workflow is further enhanced by PyFreeFEM (developed by Florian Feppon) for high-level scripting and automated execution, PyTorch for integrating deep-learning-based models, and MATLAB for phasor-based de-homogenisation post-processing.

2025/md/HL.md

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+## Mathematical Aspects of ANM/FEM Numerical Model, Applied to Nonlinear Elastic, and Thermo Elastic Analysis of Wrinkles in Film/Substrate Systems,
+## Dr Pascal Ventural,,[email protected]
+
+## LEM3, Université de Lorraine
+
+
+*Abstract:* Mathematical Aspects of ANM/FEM Numerical Model, Applied to Nonlinear Elastic, and Thermo Elastic Analysis of Wrinkles in Film/Substrate Systems, and a New Implementation in the FreeFEM++ Language The main purposes of the present work are to present the mathematical and algorithmic aspects of the ANM/FEM numerical model and to show how it is applied to analyze elastic and thermo-elastic nonlinear solid mechanical problems. ANM is a robust continuation method based on a perturbation technique for solving nonlinear problems dependent on a loading parameter. Historically, this technique has been successfully applied to problems in various fields of solid and fluid mechanics. We will show how ANM is used to solve nonlinear elastic and nonlinear thermo-elastic problems involving elastic behavior and geometrical nonlinearities. The implementation of ANM for FEM in the FreeFEM++ language is then presented. The new numerical model is applied to study wrinkles appearing in a planar film/substrate system that is subjected to compressive surface forces at the lateral faces of the film. Finally, the model is applied to a spherical film/substrate system subjected to thermo-elastic shrinkage. In both cases, the ANM/FEM prediction method, together with a Newton–Riks correction (if needed), identifies the equilibrium paths efficiently, especially after the post-buckling regime.

2025/md/PV.md

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+## Optimization of a 2D Molten Salt Reactor benchmark with FreeFEM 
+## MR Ruggero Rosselli  [email protected]
+
+## CEA Saclay
+
+
+*Abstract:* Due to the nature of Molten Salt Reactors (MSRs), a great effort is dedicated to the development of high-fidelity multi physics tools to accurately take into account the interactions between the different physics at play. While sensitivity analysis procedures exist and are common for "single physics" problems, such as Generalized Perturbation Theory (GPT) for neutronics, such procedures are less common for multi physics problems. The goal is then to develop an efficient adjoint sensitivity analysis method for a coupled neutronics - thermal hydraulics MSR. First, the 2D neutronics - thermal hydraulics benchmark problem is calculated with FreeFEM, using the native Lagrange elements. The results obtained are compared to those available in the literature, showing acceptable discrepancies (with maxima of about 2%). Then, choosing a specific response function, the adjoint problem is implemented in FreeFEM. The adjoint sensitivities of the response function are calculated with respect to the input parameters of the problem and compared to finite differences calculations, showing excellent agreement. FreeFEM proves to be an excellent, flexible tool to implement adjoint methods for reactor physics problems.