Responsable du programme de Chirurgie Cardiaque Congénitale Adulte à l’Hôpital de la Timone
Activités
. Chirurgie cardiaque pédiatrique et congénitale adulte
. Chirurgie cardiaque néonatale
. Réparations/plasties valvulaires
. Transplantation cardiaque pédiatrique
Axes de recherche :
. Biomécanique & Physiologie Cardiovasculaire
. Anatomie Numérique et Structurelle
. Modélisation et Simulation Cardio-Vasculaire
Profil CTSNet : https://www.ctsnet.org/home/lmace
Publications scientifiques au M2P2
2025
Loïc Macé, Luc Vandenbulcke, Jean-Michel Brankart, Jean-François Grailet, Pierre Brasseur, et al.. Three-stream modelling of radiative transfer for the simulation of Black Sea biogeochemistry in a NEMO framework. Geoscientific Model Development (GMD), 2025, ⟨10.5194/egusphere-2025-4973⟩. ⟨hal-05400857⟩ Plus de détails...
Abstract. In this paper, we propose a three-stream ocean radiative transfer (RT) module as an extension of the NEMO ocean modelling framework. This module solves the subsurface irradiance field in 1D water columns, discriminating between two downward streams, direct and scattered, and a backscattered upward stream. The module solves 33 wavebands ranging between 250 and 4000 nm, with a finer 25 nm resolution in the visible range. The sea surface reflectance is also calculated as a model output, based on the ratio between the upward and downward irradiances at the air-sea interface. An optional feedback towards NEMO is presented, enabling the use of irradiances to compute temperature in the hydrodynamics. The module also includes a stochastic version in which the inherent optical properties of the main optically active components of seawater can be perturbed. This mode is meant to account for uncertainty in the modelling of marine optics. This module is can be plugged to any NEMO configuration, with the computation of optical properties either driven by a biogeochemical model or directly forced into the RT module. We apply this module in a test case for the Black Sea, coupled with the physical-biogeochemical framework NEMO 4.2.0-BAMHBI. We find that substituting the existing radiative transfer scheme with our model unlocks the ability to simulate radiometric variables that can be compared more truthfully to observations, both in situ and from remote-sensing. We also find that using irradiances to compute the temperature and PAR in the model maintains consistency in the calculation of physical and biogeochemical variables in the model, such as temperature or chlorophyll concentration, while enabling additional capabilities in the model in the simulation of radiometric quantities.
Loïc Macé, Luc Vandenbulcke, Jean-Michel Brankart, Jean-François Grailet, Pierre Brasseur, et al.. Three-stream modelling of radiative transfer for the simulation of Black Sea biogeochemistry in a NEMO framework. Geoscientific Model Development (GMD), 2025, ⟨10.5194/egusphere-2025-4973⟩. ⟨hal-05400857⟩
Loïc Macé, Luc Vandenbulcke, Jean-Michel Brankart, Pierre Brasseur, Marilaure Grégoire. Characterisation of uncertainties in an ocean radiative transfer model for the Black Sea through ensemble simulations. Biogeosciences, 2025, 22 (15), pp.3747-3768. ⟨10.5194/bg-22-3747-2025⟩. ⟨hal-05396837⟩ Plus de détails...
Abstract. In this paper, we investigate the influence of uncertainties in inherent optical properties on the modelling of radiometric quantities by an ocean radiative transfer (RT) model, particularly irradiance and reflectance. The radiative transfer model is coupled to a 3D physical–biogeochemical model of the Black Sea. It describes the vertical propagation of incident irradiance within the water column along three streams in downward (direct and diffuse) and upward directions, with a spectral resolution of 25 nm in the visible range. The propagation of irradiance streams is governed by the inherent optical properties of four major optically active constituents found in seawater and provided by the biogeochemical model: pure water, phytoplankton, non-algal particles, and coloured dissolved organic matter (CDOM). Sea surface reflectance is then derived as the ratio between the simulated upward and downward irradiance streams, directly connecting the model with remote-sensed data. In this configuration, the coupling is one-way: the radiative transfer model is projecting model variables into the space of satellite observations, working as an observation operator. In the stochastic version of the model, uncertainties are injected in the form of random perturbations of the inherent optical properties of the water constituents. Different ensemble configurations are derived, and their quality is assessed by comparison with in situ and remote-sensed observations. We find that the modelling of the uncertainties in the radiative transfer model parameterisation allows us to simulate distributions of radiative fields that are partially consistent with observations. The ensemble is consistent with remote-sensed reflectance data in summer and autumn, especially in the central parts of the basin. The quality of the ensemble is lower in winter and early spring, suggesting the existence of another major source of uncertainty or that the quality of the deterministic solution is insufficient. CDOM dominates absorption in short wavebands with a relatively high uncertainty that influences irradiance and reflectance outputs. This dominant role calls for better representation of CDOM to improve model calibration. Contributions from phytoplankton and non-algal particles are more significant for (back)scattering. The results of this paper suggest that the integration of a radiative transfer model into a physical–biogeochemical model would be beneficial for calibration, validation, and data assimilation purposes, offering a better link between model variables and radiometric observations.
Loïc Macé, Luc Vandenbulcke, Jean-Michel Brankart, Pierre Brasseur, Marilaure Grégoire. Characterisation of uncertainties in an ocean radiative transfer model for the Black Sea through ensemble simulations. Biogeosciences, 2025, 22 (15), pp.3747-3768. ⟨10.5194/bg-22-3747-2025⟩. ⟨hal-05396837⟩
Tom Fringand, Loic Mace, Isabelle Cheylan, Marien Lenoir, Julien Favier. Analysis of Fluid–Structure Interaction Mechanisms for a Native Aortic Valve, Patient-Specific Ozaki Procedure, and a Bioprosthetic Valve. Annals of Biomedical Engineering, 2024, 52 (11), pp.3021-3036. ⟨10.1007/s10439-024-03566-1⟩. ⟨hal-04928780⟩ Plus de détails...
The Ozaki procedure is a surgical technique which avoids to implant foreign aortic valve prostheses in human heart, using the patient’s own pericardium. Although this approach has well-identified benefits, it is still a topic of debate in the cardiac surgical community, which prevents its larger use to treat valve pathologies. This is linked to the actual lack of knowledge regarding the dynamics of tissue deformations and surrounding blood flow for this autograft pericardial valve. So far, there is no numerical study examining the coupling between the blood flow characteristics and the Ozaki leaflets dynamics. To fill this gap, we propose here a comprehensive comparison of various performance criteria between a healthy native valve, its pericardium-based counterpart, and a bioprosthetic solution, this is done using a three-dimensional fluid–structure interaction solver. Our findings reveal similar physiological dynamics between the valves but with the emergence of fluttering for the Ozaki leaflets and higher velocity and wall shear stress for the bioprosthetic heart valve.
Tom Fringand, Loic Mace, Isabelle Cheylan, Marien Lenoir, Julien Favier. Analysis of Fluid–Structure Interaction Mechanisms for a Native Aortic Valve, Patient-Specific Ozaki Procedure, and a Bioprosthetic Valve. Annals of Biomedical Engineering, 2024, 52 (11), pp.3021-3036. ⟨10.1007/s10439-024-03566-1⟩. ⟨hal-04928780⟩
Tom Fringand, Isabelle Cheylan, Marien Lenoir, Loic Mace, Julien Favier. A stable and explicit fluid–structure interaction solver based on lattice-Boltzmann and immersed boundary methods. Computer Methods in Applied Mechanics and Engineering, 2024, 421, pp.116777. ⟨10.1016/j.cma.2024.116777⟩. ⟨hal-04971126⟩ Plus de détails...
Fluid-structure interaction (FSI) occurs in a wide range of contexts, from aeronautics to biological systems. To numerically address this challenging type of problem, various methods have been proposed, particularly using implicit coupling when the fluid and the solid have the same density, i.e., the density ratio is equal to 1. Aiming for a computationally efficient approach capable of handling strongly coupled dynamics and/or realistic conditions, we present an alternative to the implicit formulation by employing a fully explicit algorithm. The Lattice Boltzmann Method (LBM) is used for the fluid, with the finite element method (FEM) utilized for the structure. The Immersed Boundary Method (IBM) is applied to simulate moving and deforming boundaries immersed in fluid flows. The novelty of this work lies in the combination of Laplacian smoothing at the fluid/solid interface, an improved collision model for the LBM, and a reduction of non-physical frequencies on the structure mesh. The use of these adaptations results in a solver with remarkable stability properties, a primary concern when dealing with explicit coupling. We validate the numerical framework on several challenging test cases of increasing complexity, including 2D and 3D configurations, density ratio of 1, and turbulent conditions.
Tom Fringand, Isabelle Cheylan, Marien Lenoir, Loic Mace, Julien Favier. A stable and explicit fluid–structure interaction solver based on lattice-Boltzmann and immersed boundary methods. Computer Methods in Applied Mechanics and Engineering, 2024, 421, pp.116777. ⟨10.1016/j.cma.2024.116777⟩. ⟨hal-04971126⟩
Journal: Computer Methods in Applied Mechanics and Engineering
