Publications

2025

• Bayesian inference of numerical modeling-based morphodynamics: Application to a dam-break over a mobile bed experiment
  
  • Goeury Cédric
  • Souillé Fabien
  Computational Geosciences, Springer Verlag, 2025, 30 (1), pp.2. Numerical modeling of morphodynamics presents significant challenges in engineering due to uncertainties arising from inaccurate inputs, model errors, and limited computing resources. Accurate results are essential for optimizing strategies and reducing costs. This paper presents a step-by-step Bayesian methodology to conduct an uncertainty analysis of 2D numerical modeling-based morphodynamics, exemplified by a dam-break over a sand bed experiment. Initially, uncertainties from prior knowledge are propagated through the dynamical model using the Monte Carlo technique. This approach estimates the relative influence of each input parameter on results, identifying the most relevant parameters and observations for Bayesian inference and creating a numerical database for emulator construction. Given the computationally intensive simulations of Markov chain Monte Carlo (MCMC) sampling, a neural network emulator is used to approximate the complex 2D numerical model efficiently. Subsequently, a Bayesian framework is employed to characterize input parameter uncertainty variability and produce probability-based predictions. (10.1007/s10596-025-10400-7)
  DOI : 10.1007/s10596-025-10400-7
• Construction and performance of kinetic schemes for linear systems of conservation laws
  
  • Audusse Emmanuel
  • Boyaval Sébastien
  • Dubos Virgile
  • Le Minh-Hoang
  , 2025. We describe a methodology to build vectorial kinetic schemes, targetting the numerical solution of linear symmetric-hyperbolic systems of conservation laws -a minimal application case for those schemes. Precisely, we fully detail the construction of kinetic schemes that satisfy a discrete equivalent to a convex extension (an additional non-trivial conservation law) of the target system -the (linear) acoustic and elastodynamics systems, specifically -. Then, we evaluate numerically the convergence of various possible kinetic schemes toward smooth solutions, in comparison with standard finite-difference and finite-volume discretizations on Cartesian meshes. Our numerical results confirm the interest of ensuring a discrete equivalent to a convex extension, and show the influence of remaining parameter variations in terms of error magnitude, both for "first-order" and "second-order" kinetic schemes : the parameter choice with largest CFL number (equiv., smallest spurious diffusion in the equivalent equation analysis) has the smallest discretization error.
• Biomechanical finite element simulation of the pelvic organs under dynamic loading and validation against experimental data from magnetic resonance imaging
  
  • Lafond Camille
  • Hohnadel Louise
  • Brunel Thomas
  • Pirrò Nicolas
  • Bellemare Marc-Emmanuel
  • Chamoret Dominique
  • Roth Sébastien
  Medical Engineering & Physics, Elsevier, 2025, 146, pp.104433. Pelvic organ prolapse (POP) is a prevalent condition affecting women, particularly those over the age of 50. The etiology and pathophysiology of this condition remain poorly understood within the medical community. In recent years, researchers, particularly medical engineers and biomechanical scientists, have initiated studies on this female pathology. Numerous finite element analyses have been conducted to determine the material properties of tissues involved in POP. Building on the material properties established in prior research, this study presents a patient-specific model derived from patient-specific MRI data. Intra-abdominal pressure (IAP) and boundary conditions were determined from MRI analysis, and the models were validated against MRI simulations encompassing 11 seconds with a 1-second step interval. This study compares the outcomes of our models with MRI results, providing insights into POP biomechanics. A good correlation was observed between MRI data and the finite element method (FEM) models in healthy patients, particularly for the bladder when fluid properties, such as urine, were included. A relative error between 18% and 26% was observed for bladder displacement. Moreover, the models provided acceptable results for the uterus, vagina, and rectum. Visual results supporting these findings are presented in this study. (10.1016/j.medengphy.2025.104433)
  DOI : 10.1016/j.medengphy.2025.104433
• Numerical simulation of nearshore wave propagation and overtopping of coastal protections with weakly dispersive phase-resolving models
  
  • Coulaud Guillaume
  , 2025. The goal of this thesis is to develop and validate a numerical modelling approach for the deterministic (or phase resolving) simulation of nearshore wave propagation, as well as wave overtopping of coastal protections, in realistic configurations. More specifically, this work aims at examining the applicability of weakly-dispersive Boussinesq-type models for this purpose, both in one and two horizontal dimensions.The research starts with a comprehensive theoretical and numerical comparison of eight Boussinesq-type and Serre-Green-Naghdi (SGN)-type models, either weakly or fully nonlinear, for the propagation of non-breaking long waves. These models are first assessed in terms of their theoretical dispersive, nonlinear, and shoaling properties. Their capacity to simulate coastal wave propagation and their transformation when approaching the shore is assessed on three challenging one-dimensional benchmarks. The analysis identifies the most accurate and robust formulations for modelling wave transformation in coastal zones. This work was published in Coastal Engineering (Coulaud et al., 2025).To investigate the applicability of such models for simulating wave overtopping, a one-dimensional numerical model, based on the enhanced Serre-Green-Naghdi (eSGN) equations of Bonneton et al. (2011), was developed. A hybrid finite volume and finite difference scheme is used to discretise the equations, with a simple and robust treatment of moving shorelines. Wave breaking is modelled with an eddy viscosity approach, by adding a diffusive-like energy dissipation term. The dissipation is controlled by an eddy viscosity based on the turbulent kinetic energy (TKE), which is computed by solving an additional transport equation. This model has been used e.g. in Kazolea & Ricchiuto (2018) and is both robust and accurate at describing surf-zone processes. The model is validated with several standard test cases or laboratory experiments of wave propagation, shoaling and breaking (covering solitary, regular and irregular waves).The model is then applied to reproduce two sets of one-dimensional overtopping experiments in wave flumes, totalling 184 cases. They allow for assessing its ability to accurately simulate wave propagation from offshore to the toe of coastal protections, as well as to reproduce average discharges overtopping the structure. The experiments cover several orders of magnitude of overtopping discharges, with both breaking and non-breaking waves, and unimodal or bimodal spectra. Comparisons with state-of-the-art semi-empirical formulae of the EurOtop (2018) manual for estimating overtopping discharges are also presented.The development of a two-dimensional model on structured grids is then presented, also based on the eSGN equations of Bonneton et al. (2011) and the TKE wave breaking model. The discretisation is based on finite volume/finite difference numerical methods like those used for the one-dimensional model. The model is validated with several laboratory experiments of wave propagation and breaking. Finally, its operational applicability is demonstrated by applying it to reproduce two-dimensional laboratory experiments (in a wave basin) of irregular wave propagation, breaking and overtopping of a vertical wall. (10.70675/e5e12f67z55d0z4aa3zaa8az77dcdf90e0cd)
  DOI : 10.70675/e5e12f67z55d0z4aa3zaa8az77dcdf90e0cd
• Global solutions and uniform convergence stability for compressible Navier-Stokes equations with oldroyd-type constitutive law
  
  • Wang Na
  • Boyaval Sébastien
  • Hu Yuxi
  Mathematical News / Mathematische Nachrichten, Wiley-VCH Verlag, 2025. We consider one dimensional isentropic compressible Navier-Stokes equations with Oldroyd-type constitutive law. By establishing uniform a priori estimates (with respect to relaxation time), we show global existence of smooth solutions with small initial data. Moreover, we get global-in-time convergence of the system towards the classical isentropic compressible Navier-Stokes equations. (10.1002/mana.70075)
  DOI : 10.1002/mana.70075
• Mesure de l'érosion des sables : quand le numérique et l'expérimental se complètent
  
  • Larrarte Frédérique
  • Nicolas Xavier
  • Merzoud Massinissa
  • Michard Clément
  • Gomit Guillaume
  • Cadet Simon
  • Jarny Sébastien
  • Chevalier Christophe
  , 2025.
• Modelling drainage-surface exchanges with TELEMAC-SWMM at the scale of a neighbourhood
  
  • Lapillonne Suzanne
  • Bourban Sébastien E
  • Camazzola Alan
  • Mignot Emmanuel
  • Riviere Nicolas
  • Proust Sébastien
  • Lipeme Kouyi Gislain
  , 2025. Urban drainage system failures are becoming more and more common due to the increase in magnitude and frequency of extreme rainfall events and pose significant safety and sanitary risks for urban populations during urban flooding. Practitioners involved in urban planning need comprehensive numerical tools to accurately describe the interplay between flows in the drainage network and floodwaters in the street network during extreme rainfall. EDF R&D, France, and Yuansuan, China, have recently coupled TELEMAC with the stormwater management software SWMM, from the US-EPA, under the git development branch called "swordtail". This branch is available to developers for testing and validation. The coupled system is initially tested against experimental data from a 2×2 street network only (no sewer network), investigated by Mejia-Morales [2021] where numerical parameters are calibrated for the experimental platform, with errors below 3% for flow rates and 5% for flow depths. Building on this calibration, a second case study investigates a surface-todrainage scenario based on experimental observations of a 3×3 street network with 12 drains by Camazzola et al. [2025]. The model is able to reproduce flow rates through the drains, discharge in the main street, and qualitative flow structures such as swirling eddies.
• Calibration of roughness for flood modeling using satellite data
  
  • Travert Jean-Paul
  , 2025. Flood simulation commonly relies on two-dimensional (2D) hydrodynamic models, which must be carefully calibrated and validated using past flood events to ensure accurate forecasting. A critical component of this calibration process is the spatial distribution of the roughness parameter, which significantly influences simulated water depths and velocities. In the minor bed, the hydrodynamic models are calibrated using time-series data from stage-gauging stations. For floodplains, few data are available, and the roughness spatial distribution is often poorly known and typically inferred from land-use classifications using empirical values drawn from expert judgment. Hydrodynamic models' calibration could benefit from incorporating the maximum available observational data.In this context, satellite remote sensing can be leveraged as a valuable source of information. Synthetic Aperture Radar (SAR) imagery, in particular, is capable of detecting surface water extents even under cloud cover, making it highly suitable for flood monitoring. This thesis aims to develop a methodology to calibrate floodplain roughness coefficients in 2D hydrodynamic models, leveraging satellite-derived observations.The first step aims to recover information from the satellite observations to calibrate the flood models. Thus, this thesis proposed an evaluation of the extraction of flood extent maps and water depth fields from SAR imagery, along with an evaluation of the associated uncertainties arising from method choices and hyperparameter settings. The flood extent maps should be compared with the hydrodynamic model to calibrate it. Thus, in this thesis, we developed a step-by-step methodology to guide the selection of appropriate performance measures to compare simulated and observed flood extent maps. Then, the uncertain SAR-derived flood observations are integrated into the hydrodynamic modeling framework through data assimilation techniques to enhance the calibration of spatially distributed roughness coefficients on floodplains.By combining remote sensing data, uncertainty quantification, and hydrodynamic modeling, this thesis proposes an approach to enhance flood model calibration, with the potential to improve flood forecasting and risk management practices. (10.70675/8e558e53zdc51z4af5z982fze333489f231e)
  DOI : 10.70675/8e558e53zdc51z4af5z982fze333489f231e
• Resolved DEM-CFD coupling for wave-armour blocks interactions
  
  • Barcet Matthieu
  • Benguigui William
  • Laviéville Jérôme
  • Benoit Michel
  • Wachs Anthony
  • Fede Pascal
  • Bonometti Thomas
  Ocean Engineering, Elsevier, 2025, 337, pp.121865. The present work aims to tackle breakwater stability challenges through an innovative numerical deterministic method using a resolved DEM-CFD (Discrete Element Method—Computational Fluid Dynamics) strategy, which simulates the individual motions of armour units within a fluid solver. To achieve this, a coupling between a DEM code and a CFD code is implemented and validated. The fluids (air and water) are solved using a Eulerian–Eulerian CFD solver, and the contacts between blocks are solved using a DEM code. The solids are defined within the fluid solver using a discrete forcing approach and are therefore fully resolved. In this way, the fluid solver enables the prediction of object motions with complex shapes such as tetrapods. To couple the codes, forces exerted on the solids are calculated in the fluid solver and sent to the DEM solver. Then, contact and gravity forces are computed and added to the fluid forces. The DEM solver then computes the new positions and velocities of the bodies, which are retrieved by the fluid solver. An experimental study is performed on a fixed and instrumented idealized breakwater to evaluate the wave forces acting on a coastal structure. The experiments are then numerically reproduced to validate the numerical model. Simulations of the impact of solitary waves on a row of mobile isolated tetrapods laid on a horizontal berm are then performed using the DEM-CFD coupling. The importance of initial placement and friction parameters is investigated to show the sensitivity to these parameters. (10.1016/j.oceaneng.2025.121865)
  DOI : 10.1016/j.oceaneng.2025.121865
• L'hydrodynamique des vagues du large jusqu'à la côte : modélisation et impacts
  
  • Benoit Michel
  • Harris Jeffrey
  • Yates Marissa
  Transitions. Les nouvelles Annales des Ponts et Chaussées, École des Ponts ParisTech et Presses des Ponts, 2025 (5), pp.44-48.
• Blowup of solutions for compressible viscoelastic fluid
  
  • Wang Na
  • Boyaval Sébastien
  • Hu Yuxi
  Procedia Materials Science (Elsevier), Elsevier, 2025. We prove finite-time blowup of classical solutions for the compressible Upper Convective Maxwell (UCM) viscoelastic fluid system. By establishing a key energy identity and adapting Sideris' method for compressible flows, we derive a Riccati-type inequality for a momentum functional. For initial data with compactly supported perturbations satisfying a sufficiently large condition, all classical solutions lose regularity in finite time. This constitutes the first rigorous blowup result for multidimensional compressible viscoelastic fluids. (10.1016/j.aml.2025.109774)
  DOI : 10.1016/j.aml.2025.109774
• A tree-based Polynomial Chaos expansion for surrogate modeling and sensitivity analysis of complex numerical models
  
  • Ben Said Faten
  • Alfonsi Aurélien
  • Dutfoy Anne
  • Goeury Cédric
  • Jodeau Magali
  • Reygner Julien
  • Zaoui Fabrice
  , 2025. This paper introduces Tree-based Polynomial Chaos Expansion (Tree-PCE), a novel surrogate modeling technique designed to efficiently approximate complex numerical models exhibiting nonlinearities and discontinuities. Tree-PCE combines the expressive power of Polynomial Chaos Expansion (PCE) with an adaptive partitioning strategy inspired by regression trees. By recursively dividing the input space into hyperrectangular subdomains and fitting localized PCEs, Tree-PCE constructs a piecewise polynomial surrogate that improves both accuracy and computational efficiency. The method is particularly well-suited for global sensitivity analysis, enabling direct computation of Sobol' indices from local expansion coefficients and introducing a new class of sensitivity indices derived from the tree structure itself. Numerical experiments on synthetic and real-world models, including a 2D morphodynamic case, demonstrate that Tree-PCE offers a favorable balance between accuracy and complexity, especially in the presence of discontinuities. While its performance depends on the compromise between the number of subdomains and the degree of local polynomials, this trade-off can be explored using automated hyperparameter optimization frameworks. This opens promising perspectives for systematically identifying optimal configurations and enhancing the robustness of surrogate modeling in complex systems.
• Numerical modelling of nearshore wave transformation, breaking and overtopping of coastal protections with the enhanced Serre-Green–Naghdi equations
  
  • Coulaud Guillaume
  • Teles Maria
  • Benoit Michel
  Coastal Engineering, Elsevier, 2025. Admissible average overtopping discharges in given storm conditions are typically used to design coastal protections, in particular dykes or breakwaters. These discharges are usually estimated using semi-empirical formulas relying on wave conditions at the toe of the structure. These formulas, unfortunately, only work for simple configurations, invariant alongshore, and can be insufficient for complex sea states. Therefore, numerical modelling could be a more flexible alternative for estimating these discharges. This work presents the development and validation of a Boussinesq-type numerical model solving the fully-nonlinear weakly-dispersive enhanced Serre-Green-Naghdi equations for the simulation of random wave overtopping over impermeable structures in one horizontal dimension. Wave breaking is modelled with an eddy viscosity approach based on the turbulent kinetic energy, which is robust and accurate at describing energy dissipation in the surf zone. Two distinct experimental datasets, with 184 trials in total and very dissimilar wave conditions and foreshore seabed profiles, are used to validate the model regarding wave propagation, shoaling, breaking and overtopping. Both unimodal and bimodal sea states are considered. Average overtopping discharges in configurations with deep and very shallow foreshores, as well as for breaking and non-breaking waves, are well reproduced by the model. For instance, typical mean relative errors on the simulated mean overtopping rates are found to lie within ±20% compared with the measurements, at least for the largest discharges of the considered campaigns. The scatter of simulated discharges is somewhat higher for lower discharges, but the results remain in an acceptable range. (10.1016/j.coastaleng.2025.104857)
  DOI : 10.1016/j.coastaleng.2025.104857
• Force - frequency relationship in front crawl swimming
  
  • Brunel Thomas
  • Clanet Christophe
  • Larrarte Frédérique
  • Cohen Caroline
  • Carmigniani Rémi
  , 2025. Force - frequency relationship in front crawl swimming
• Evaluation of Performance Measures for Comparing Flood Models With Satellite Observations
  
  • Travert Jean-Paul
  • Boyaval Sébastien
  • Goeury Cédric
  • Bacchi Vito
  • Zaoui Fabrice
  Water Resources Research, American Geophysical Union, 2025, 61 (8). Selecting appropriate performance measures is crucial for calibrating numerical flood models with satellite images, as differences between performance measures can significantly impact model predictions. The present study reports a step‐by‐step methodology to guide the selection of performance measures to compare numerical simulations of a flood event with a satellite image, for purposes of model calibration or validation. Faced with a set of performance measures, practitioners need to assess which are most suitable for comparing observed and simulated flood maps. First, a correlation analysis was conducted to determine the relationships between various performance measures. A series of criteria were then applied to evaluate the sensitivity of the performance measures with respect to flood extent, satellite characteristics (position and orientation), and errors in measurement or processing (raw satellite values or extraction of flood maps). The performance measures meeting the most criteria were then ranked based on the identifiability of parameter values with regard to observation errors. The methodology is discussed numerically in the context of a single flood event (on the Garonne River in France in February 2021), using a distribution of water depths simulated from a shallow‐water model (parameterized by an uncertain friction field). The methodology was shown to be useful in the study case in identifying 4 performance measures out of 24. The proposed methodology is intended to be generic, and therefore, applicable to any flood model or flood event. (10.1029/2024WR038506)
  DOI : 10.1029/2024WR038506
• Hydraulic jump analysis: Influence of negative steps and end sills on jump profile for both smooth and Dunal corrugated beds
  
  • Agrawal Nishank
  • Padhi Ellora
  • Singhal Gopal Das
  • Larrarte Frédérique
  Physics of Fluids, American Institute of Physics, 2025, 37 (8). Hydraulic jumps are the key mechanism for energy dissipation downstream o spillways; nevertheless, the intense near-bed velocities they generate can contribute to structural wear and significant scouring downstream of stilling basins. Prior studies have examined the effects of bed roughness, negative steps, and end sills individually; their combined impact remains inadequately explored. This study numerically investigates six stilling basin configurations downstream of an ogee spillway, involving different combinations of smooth and dunal corrugated beds with and without negative steps and end sills. Numerical simulations were performed using FLOW-3D for a discharge of 15 L s−1. To validate the numerical model, experimental data were collected for a dunal corrugated bed configuration, showing strong agreement with simulation results. The analysis included longitudinal velocity profiles, streamline plots, water surface elevations, total energy lines, turbulent kinetic energy, turbulence dissipation, Q-criterion vortex dynamics, etc. The results reveal that a negative step significantly reduces near-bed and depth-averaged velocities, enhancing energy dissipation. The addition of the end sill further promotes flow stability. Among all configurations, the combination of a dunal corrugated bed with a negative step (Model 4) demonstrated the highest energy dissipation and the lowest water surface elevation. Roller length was shortest for the corrugated bed and longest for the smooth bed; however, adding a negative step and end sill increased roller length while improving turbulence control. Q-criterion analysis highlights dense, coherent vortex structures in Model 4, indicating efficient turbulence mixing and energy loss. These results underscore the value of integrating bed roughness with geometric modifications. (10.1063/5.0284062)
  DOI : 10.1063/5.0284062
• Study of the environmental fate of antiscale polymers through the coupling of a numerical modeling and experimental approach
  
  • Bey Zekkoub Mohamed
  , 2025. The semi-closed cooling circuits of nuclear power plants are susceptible to mineral scaling and fouling, particularly within condenser systems and cooling towers. To mitigate calcium carbonate deposits, treatment strategies often involve acid dosing and organic scale inhibitors like sodium polyacrylate (NaPA). While effective in preventing scaling, these polymers are discharged into water bodies in dissolved and adsorbed forms, raising environmental concerns due to their affinity for suspended solids, potentially leading to accumulation in riverine ecosystems.To assess the environmental impact of sodium polyacrylate discharges, two aspects must be addressed. First, understanding the polymer’s physicochemical behavior, particularly its adsorption dynamics on mineral surfaces in varying water conditions, is essential. Second, a modeling framework is needed to simulate its fate and transport in dynamic riverine environments. Despite its industrial use, gaps remain in the literature regarding its adsorption kinetics, long-term behavior, and potential ecotoxicological effects.This thesis addresses these gaps through a multidisciplinary approach that integrates laboratory experiments with mathematical modeling. In the experimental component, batch studies characterized the adsorption kinetics and equilibrium behavior of sodium polyacrylate on sediments like kaolin and calcite found in the Seine River. The influence of key environmental variables, pH, temperature, salinity, and sediment type was investigated, leading to the calibration of a zero-dimensional (0D) adsorption kinetics submodel.In the modeling component, both numerical (1D/2D) and analytical (1D) approaches simulated the transport and adsorption of sodium polyacrylate in riverine systems. A two-dimensional numerical model was developed to solve the coupled equations governing solute dynamics, sediment transport, and polymer interactions, incorporating processes like advection and deposition. Analytical solutions provided rapid evaluation tools for predicting polymer transport under idealized conditions.Results indicate that while sodium polyacrylate poses limited short-term risk to aquatic organisms, its long-term accumulation in riverbed sediments may present greater risks to bottom organisms, especially under conditions promoting strong adsorption. Sensitivity analyses highlight the influence of seasonal flow variations, sediment composition, and polymer concentration at discharge points.By integrating experimental findings with modeling, this study offers valuable tools for predicting and assessing environmental risks associated with polymer discharges in aquatic systems. (10.70675/c0aeda88z0edaz4218z9929z88050132993f)
  DOI : 10.70675/c0aeda88z0edaz4218z9929z88050132993f
• Investigations méthodologiques et compréhension des dynamiques de transport des microplastiques dans la Seine Rencontres 2025 du GDR Plastiques Environnement Santé, Juin 2025.
  
  • Diop K.
  • Calabro-Souza Guilherme
  • Gasperi Johnny
  • Tassin Bruno
  • Mougin Jérémy
  • Krimou Rania
  • Guérin-Rechdaoui Sabrina
  • Dris Rachid
  , 2025.
• ASSESSMENT OF SODIUM POLYACRYLATE'S ENVIRONMENTAL FATE IN A RIVER REACH THROUGH EXPERIMENTS, NUMERICAL SIMULATIONS AND ANALYTICAL MODELING
  
  • Bey Zekkoub Mohamed
  • Tassi Pablo
  • Chhim Norinda
  , 2025. The accurate modeling and prediction of polymers fate when discharged in rivers is of great importance to understand their impact on aquatic and soil ecosystems. This study presents a comprehensive investigation into the environmental fate of sodium polyacrylate, used polymer across many industries, in a reach of the Seine River through an integrated approach combining laboratory experiments, numerical simulations performed using the openTELEMAC system, and analytical modeling. Laboratory adsorption experiments were conducted to investigate its adsorption for calcite and kaolin, minerals representative of suspended sediments in the Seine River. The hydrodynamics results obtained using TELEMAC-2D were validated using velocity field measurements. One-dimensional analytical solutions were derived and first used to validate numerical simulations for the polymer concentrations obtained using WAQTEL-MICROPOL in controlled flume-like configuration, and subsequently applied to the Seine River reach to assess their applicability in complex riverine systems. The laboratory experiments were used to validate the adsorption sub-model named "the one-step reversible model", and therefore the adsorption parameters obtained from model calibration were incorporated into the river model to investigate the impact of suspended sediments mineralogical composition on sodium polyacrylate transport and fate. This multidisciplinary approach enhances our understanding of polymers behavior in aquatic environments, providing valuable insights for environmental management and pollution mitigation strategies. (10.64697/978-90-835589-7-4_41WC-P1698-cd)
  DOI : 10.64697/978-90-835589-7-4_41WC-P1698-cd
• SPH modelling of water flow inside a porous medium using a Riemann based formulation
  
  • de Sousa Coline
  • Oger Guillaume
  • Michel Julien
  • Le Touzé David
  • Violeau Damien
  , 2025. Simulating granular flows has been a major concern for the past decades, with various environmental applications such as avalanches, landslides and scour near fluvial, coastal and off- shore constructions. These phenomena involve a porous matrix undergoing large deformations and characterized by a complex behaviour. Thanks to its ability to handle large deformations of the medium, SPH appears as a particularly advantageous method to deal with these problems. Various SPH schemes already exist to model the granular medium behaviour, such as the ones developed by Feng et al. [1], Bui and Nguyen [2] (elastoplastic approach) or Gha¨ıtanellis [3] (elasto-viscoplastic approach). However, to the authors’ knowledge, none of these papers show in their results what the water flow looks like inside the porous structure while it deforms. Consequently, the present work aims at presenting a model to simulate the deformation of a granular medium as well as its infiltration by water. The porous structure is unsaturated and is considered as a continuous medium. Infiltrated water flows according to Darcy’s or Darcy- Forchheimer’s laws. Two different sets of particles are used for this purpose, one for the water phase and an other one for the porous structure, as done by Shimizu et al [4]. Riemann- based schemes have never been used yet for such purpose, though it proved to give accurate results for both fluid [6] and solid mechanics [7]. As a consequence, a new approach is proposed here by applying Riemann-based formulations on both fluid and solid media. For the moment, the proposed model is not yet finished developing and only simulations with undeformable porous matrix are available for the writing of this abstract. Results with moving, deformable porous matrix will be presented during the conference.
• On a high-order shallow-water wave model with canonical non-local Hamiltonian structure
  
  • Papoutsellis Christos
  • Benoit Michel
  Physica D: Nonlinear Phenomena, Elsevier, 2025, 479, pp.134691. We derive and study a new family of non-local partial differential equations (PDEs) that model free-surface long gravity waves over a flat bottom. To derive the model equations we approximate the velocity potential as a series of vertical polynomials derived from the shallow-water expansion of the Dirichlet-to-Neumann problem in the Hamiltonian formulation of free-surface potential flow and invoke Luke's variational principle. The resulting evolution equations exhibit a non-local Hamiltonian structure being coupled with a system of linear elliptic spatial PDEs on the horizontal plane. A key advantage of this approach is that it directly yields canonical Hamiltonian equations, which are well-suited for numerical solutions using standard methods. This class of model equations offers high-order shallow-water approximations of the water-wave problem. It contains terms whose spatial derivatives are at most of order two, distinguishing it from asymptotic methods involving higher-order mixed spatio-temporal derivatives. We explore the first non-trivial member of this family, highlighting its connections to other mathematical models and emphasizing its practical utility. We then analyze and discuss its linear dispersive properties and demonstrate that it does not exhibit a specific type of instability known as wave-trough instability. Additionally, we demonstrate its effectiveness in simulating the long-distance steady propagation of strongly non-linear solitary waves and the head-on collision of two counter-propagating solitary waves. In the latter case, comparisons with experimental data confirm the model's ability to capture complex wave dynamics, including wave transformation in the presence of strong non-linearity and dispersion. The extension of this approach to accommodate variable bottom topography is briefly discussed. (10.1016/j.physd.2025.134691)
  DOI : 10.1016/j.physd.2025.134691
• Statistical modelling of combined sewer overflow
  
  • Cartier Yoann
  • Guillot-Le Goff Arthur
  • Carmigniani Rémi
  • Métivier David
  • Einfalt Thomas
  • Vinçon-Leite Brigitte
  • Kennouche Paul
  , 2025, pp.22 p.. Rivers are at the heart of human activity. They provide many ecosystem services: drinking water, agriculture, transport, hydropower, bathing, freshness, etc. They are also hotspots for biodiversity. However, the water quality of these rivers is deteriorated as a result of human activity. The current work focuses on fecal contamination, which is a discriminating criterion for bathing. In urban watersheds, fecal bacteria contamination comes from point sources related to the operation of the drainage network. During rainy weather, the combined sewer network, mixingboth wastewater and stormwater, can become saturated. As a consequence, part of the flow is discharged directly into the river via combined sewer overflows (CSOs). This is the case for the city of Paris. The possible CSO overflow can be modeled by a function linking its discharge toprecipitation. This relationship is currently poorly understood, with little related work, and even less for the Seine river.To build such linking function, we rely on a dataset that includes location and hourly discharged volume of the monitored CSOs in the Seine River within Paris. Urban watersheds have been delineated within the study site. Rainfall height over these watersheds have been obtained from eather radar. We broke down the data timeseries into events. An event begins with the cause, the rain, and ends with the consequence, the overflow. To link rainfall to CSOs a directional graph based on the drainage network map, was created. It represents the wastewater transport from one watershed to another. This highlights which rainfall variables to consider regarding the CSO location. Principal component analysis (PCA) is used to assess for rain characteristics selection. An unsupervised non-linear technique (Isomap) is then used to build linking function structure.The overflow volume in time can be modeled by a triangular shape. This shape is described by the overflow initial time, its total and maximum volume and the time of the maximum. We expect to retrieve these overflow variables by reducing the number of rainfall event characteristics to single indicators using sequentially PCA and Isomap.Modeling and forecasting source discharges would enable better management of bathing and water supply risks, and better evaluation of mitigation infrastructures. (10.5194/egusphere-egu25-11965)
  DOI : 10.5194/egusphere-egu25-11965
• MODELLING SHORELINE DYNAMICS IN COMPLEX MACROTIDAL ENVIRONMENTS USING NEURAL NETWORKS
  
  • Mingorance Gabriel
  • Sénéchal Nadia
  • Bertin Stéphane
  • Floc'H France
  • Suanez Serge
  • Yates Marissa L.
  , 2025. <div><p>The aim of this work is to test an artificial intelligence approach with basic hydrodynamic and morphological variables, in order to assess the effectiveness of such methods in modelling complex beach dynamics. A simple feedforward neural network is used to evaluate the impact of selected variables on the prediction of the dynamics of specific shoreline isocontour proxies extracted from beach profiles, and to build a predictive model that could simulate the position of the proxies. The model was trained on datasets from two sites from the French coastal monitoring program DYNALIT, Porsmilin and Vougot beaches, and their profile measurements, water levels and wave measurements over 20 years. These two sites were selected due to differences in their morphology and hydrodynamics, as a means to assess the performance of neural networks over a larger variety of situations. A range of temporalities encompassing 3 days, 7 days, 14 days, and 30 days of selected hydrodynamic and morphological variables were used to study the impact time scales can have on modelled shoreline positions. The shoreline proxies used for Porsmilin and Vougot beaches correspond respectively to the berm and the contact between the dune toe and the upper beach, which can be assessed and followed along each beach profile. The shallow feedforward network included 1 hidden layer and 5 nodes, and was ran 50 times in order to assess the models' performance. The models were generally successful, with a blind shoreline prediction R of 0.88 in Porsmilin and 0.72 in Vougot. This artificial neural network (ANN) approach showed all-around better performance than previous beach equilibrium models, which is very encouraging regarding the prediction of future beach morphodynamics and the use of Machine Learning algorithms therein.</p></div>
• Three-dimensional numerical modeling of sediment transport in a highly turbid estuary with pronounced seasonal variations
  
  • Do Thi-Kim-Anh
  • Huybrechts Nicolas
  • Jalón-Rojas Isabel
  • Tassi Pablo
  • Sottolichio Aldo
  International Journal of Sediment Research, Elsevier, 2025, 40 (2), pp.333-347. Simulating sediment dynamics in a large and energetic estuary system remains challenging, primarily due to the spatial and temporal complexities of the interaction between flow and sediment transport, especially for sand-mud mixtures. This study uses a three-dimensional (3D) numerical model, based on the open TELEMAC system, to investigate the dynamics of suspended sediment concentration (SSC) in the Gironde Estuary, a complex estuarine environment characterized by an estuarine turbidity maximum (ETM) and significant variations in river discharge. The main contributions of this study include addressing the challenges of coupling bed friction with sediment transport of the sand-mud mixture for feedback on bed roughness and bottom depth changes and the ability of the model to capture the migration of ETM from high to low flow. Additionally, the current study analyzes the ability of the model to capture the migration of ETM from high to low flow, and it utilizes a calibration strategy that minimizes parameters by using in situ data and encompassing hydroemorpho-sedimentary interactions. A sensitivity analysis was done using different settling velocity approaches and sediment classes to establish an optimal model configuration and the uncertainty associated with the reduced model parameterization is discussed. The model satisfactorily reproduces the hydrodynamic features, particularly when the hydro-sedimentary feedbacks are taken into account, the seasonal trend of SSC, springneap variations, and the development of a well-defined ETM. The selection of a specific formulation for the settling velocity influences the location and magnitude of ETM. The van Leussen formula not only predicts a broad movement of ETM from high to low river flow, but also predicts high turbidity for extended periods during low river flow. Conversely, two empirical formulas from Le Hir and Defontaine predicted the highest turbidity during neap tides but sediment losses during prolonged simulations. The results of this study contribute to a deeper understanding of sediment dynamics in the Gironde Estuary, providing valuable information for future estuarine modeling and management. (10.1016/j.ijsrc.2024.12.003)
  DOI : 10.1016/j.ijsrc.2024.12.003
• Imbalance Term in the TKE Budget over Waves
  
  • Vonta Linta
  • Bourras Denis
  • Benjeddou Saïd
  • Luneau Christopher
  • Touboul Julien
  • Fraunié Philippe
  • Sentchev Alexei
  • Villefer Antoine
  Atmosphere, MDPI, 2025, 16 (4), pp.412. In an attempt to reconciliate air-sea momentum flux estimates derived from open sea observations, from large eddy simulation output fields, and from wind-wave tank measurements, a series of dedicated experiments were conducted in the wind-wave tank of the Large Air-Sea Facility of Marseille, France. The turbulent friction velocity, upon which the momentum flux depends, was estimated from wind measurements by applying four classical methods including the eddy-covariance method and the inertial-dissipation method. The collected data were used to investigate some characteristics of the waveinfluenced boundary layer that were predicted by previous simulations, and to quantify a wave-dependent term of the turbulent kinetic energy equation, the so-called imbalance term ϕ imb . Our results show that the turbulent stress decreases toward lower heights where the effect of waves is large, as in the simulations, and that ϕ imb is in the range 0.3 to 0.7, which is comparable to the value found with open sea data (0.4). These preliminary results have to be confirmed with wave-following probes, because the estimated eddy-covariance flux slightly varied with height, thus it could not be strictly considered to be equal to a constant total flux. (10.3390/atmos16040412)
  DOI : 10.3390/atmos16040412