# Members

MEMA

# Applied mechanics and mathematics

Secteur des sciences et technologies

MEMA

Euler

Avenue Georges Lemaître 4-6, boîte L4.05.02,

1348, Louvain-la-Neuve

Avenue Georges Lemaître 4-6, boîte L4.05.02,

1348, Louvain-la-Neuve

+32 10 47 21 80

completed his master in Applied Mathematics at Université catholique de Louvain: he did an Erasmus year at Royal Institute of Technology and he performed his master thesis within Cenaero's Argo team. He realized a PhD thesis between the Université de Liège and Université catholique de Louvain, under the supervision of Prof. Christophe Geuzaine and Prof. Jean-François Remacle. His research work was related to surface reparameterizations, two-dimensional crossfield computation and 3D frame representation. He was funded by ARC WAVES project 15/19-03. |

The aim of the project is to realize multibloc decomposition of 3D volumes in order to generate full hex meshes. Nowadays, this kind of decomposition is done by hand. The purpose of this work is to be able to do it in an automatic way. In order to reach this objective, we are generating 3D crossfields in this volume to locate singular points and automatize the decomposition. |

graduated in mathematical engineering at Université catholique de Louvain (Belgium) in 2016 and is presently pursuing a PhD under the supervision of Prof. V. Legat. The goal of his thesis is to develop an hybrid multiscale model for immersed granular flows. On one hand, the motion of the grains is obtained by a discrete element method at the granular scale. On the other hand, modified Navier-Stokes equations for porous media are solved to compute the mixture flow using a finite element method at a greater scale than the grains scale. Such a model can be used to represent highly inhomogeneous immersed granular flows going from pure fluid to porous media. The discrete representation of the grains will provide the possibility to discribe accurately the physics of the grains and their interaction with complex geometries while the continuous representation of the mixture will induce a reduced computational time. |

graduated in physical engineering at Université Catholique de Louvain in 2018 and is currently pursuing a PhD under the supervision of Prof. Vincent Legat. The goal of his thesis is to study the performance of the MigFlow Software using applications that require the management of frictional contacts. |

Technician |

Ruiyang DAI completed his master in Mechanical Engineering at Ecole Centrale de Nantes in France in 2016. Now he is a PhD student at Université catholique de Louvain on Fast Helmholtz solvers on Multi-Threaded Atchitectures under the supervision of Prof. Jean-François Remacle and Prof. Christophe Geuzaine. |

Within the field of solid mechanics, my research aims at an improved understanding of the influence of microstructure and damage on the deformability, the strength and the toughness of both natural and high-performance engineering materials. One important challenge is to address anisotropic, non-linear and possibly unstable responses resulting from microstructural changes in plastically deformed heterogeneous materials. To assist the interpretation of experimental observations, performed at various length scales, I develop original, physically-sound, constitutive models and apply them in computational predictions of the microscopic and macroscopic mechanical response. The fields of application span many engineering disciplines, among which mechanical manufacturing, biomechanics and structural integrity. |

has a degree in electrical and mechanical engineering, and a doctorate in applied sciences (mechanics). His research interests focus on the development and use of unstructured-mesh models for simulating geophysical and environmental fluid flows, as well as the related ecological processes. His domains of interest comprise most of the hydrosphere, i.e. lakes, rivers, estuaries, coastal regions, shelf seas and the World Ocean. He is coordinating the SLIM project (Second-generation Louvain-la-Neuve Ice-ocean Model, www.climate.be/slim) and he is the co-founder of the Constituent-oriented Age and Residence time Theory (CART, www.climate.be/cart) He has held research or teaching positions in Belgium and abroad. He currently is a reader at the Université catholique de Louvain (Louvain-la-Neuve, Belgium), where he is lecturing on several aspects of mechanics. He is also an honorary researcher with the Belgian Fund for Scientific Research (FRS-FNRS, www.fnrs.be). On October 1st, 2014, he accepted a five-year, part-time professorship in applied mathematics at the Delft University of Technology (Delft, The Netherlands, www.tudelft.be). Additional pieces of information may be found on his website (www.ericd.be). |

a Civil Engineer that graduated from The National School of Applied Sciences of Oujda, Morocco in 2017. Now she is a teaching Assistant preparing her PhD thesis under the supervision of professors Eric Deleersnijder and Vincent Legat. the topic of the thesis is: Methods of Modeling and diagnostic of transport processes in tropical river-delta-sea continuum Application to the Mahakam delta (Indonesia). |

graduated as a mechanical engineer from Ecole National d'Ingénieurs de Tunis in 2009. She first worked as a teaching fellow at the Higher Institute of Technology (Tunisia) in parallel to pursuing a research master in structural and material computational mechanics (MRes in 2010 from ENIT). Then, she joined UCL in January 2011, first as a research assistant working on the micro mechanical modeling and optimization of new materials (Carbstone) obtained by recycling slags. She has been a teaching assistant at iMMC since November 2011 and is presently pursuing a PhD under the supervision of Prof. Issam Doghri. The title of the research is micromechanical modeling of porous and composite materials. The goal of the research is to deliver models able to predict the effective mechanical behavior of materials made of at least two different phases and which can be used for complex loading tests like non-proportional loadings. The adopted technique is the Mean Field Homogenization (MFH). The development of such schemes strongly depends on the constitutive laws of the constituents. The range of materials concerned by this research is wide: elastic, viscoelastic, elasto-plastic (in the small strain regime) and hyperelastic-plastic in the finite strain regime. Her research interests also include FE analysis of cellular materials, porous materials and composites involved mainly in the validation of the MFH schemes. https://www.researchgate.net/profile/Marieme_El_Ghezal |

obtained his master in Mechanical Engineering at the National Technical University of Athens in 2015. He completed his master thesis, entitled "Non-Conformal Local Mesh Adaptation for Computation of Aerodynamic Flows", in NTUA?s Lab of Aerodynamics. He is currently a PhD student at the Université catholique de Louvain, under the supervision of Prof. Jean-François Remacle. His research project concerns boundary layer hexahedral mesh generation. |

graduated in Aerospace Engineering from Delft University of Technology, The Netherlands, in November 2013. He is currently pursuing a PhD under the supervision of Prof. Issam DOGHRI at UCL and funded by FRS-FNRS PDR project. His main thesis goal is to efficiently integrate the constitutive models of resin, fiber and fiber/matrix interface into a mulit-scale approach to predict the behavior of an uni-directional carbon-epoxy composite ply. This would require an efficient constitutive model for the resin/polymer which would address the experimentally observed features like strain-rate, temperature and pressure-dependency. So, an isotropic thermodynamically based fully coupled viscoelastic-viscoplastic model formulated under finite strain transformations was developed considering isothermal conditions, which is further extended to an anisotropic version suitable for structural composites. This model would be implemented in a multi-scale approach, with corresponding models for fiber and fiber/matrix interface, to predict softening/degradation in an uni-directional composite ply. |

completed his Engineering Degree in 1991 and his PhD in 2000, both at the University of Liège in Belgium. He then spent 4 years at the Katholieke Universiteit Leuven and 6 years at the Institut für Elektrische Maschinen in Aachen, Germany, and is now with the UCL and the ULiège. Developer in the open-source packages Gmsh, GetDP and Onelab, he has also developed skills in the multiphysics simulation of electrical machines and drives. His main interests are finite element analysis, numerical modeling, electromechanical coupling, material properties (hysteresis, iron losses, superconductors), applied mathematics (differential geometry, algebraic topology, convex analysis, dual analysis, energy methods), multiscale methods, sensitivity and optimization. |

SLIM is a simulation software which resolves the hydrodynamical equation with the use of finite elemnts. My goal is to developpe and improve the 3D model of SLIM. The two criteria are the precision of the results and the computation speed. |

completed her master in Mathematics at University of Belgrade, Serbia under the supervision of Prof. Miroslav Maric and spent a study year at Universitat de les Illes Balears, Spain under the supervision of Prof. José Juan Antonio Miró Juliá. She is currently doing a PhD at Université catholique de Louvain under the supervision of Prof. Jean-François Remacle. Her research activities are focused on poly-cube decomposition of 3D volumes. |

graduated as a physician engineer at the University of Liège (Belgium) in 2011. Then he accomplished a PhD in the topic of quadrangular mesh generation and cuvilinear mesh validation, under the supervision of professor Christophe Geuzaine. He started a postdoctoral research in January 2016 under the supervision of professor Jean-François Remacle for working on curvilinear mesh generation, hex-dominant mesh generation and mesh validation. |

obtained his phd "Finite element methods for coast flows: Application to the Great Barrier Reef" in the SLIM project at the University catholique de Louvain . He is now working as research engineer for the Institute of Mechanics, Material and Civil Engineering in the same university. His research topics include mesh generation, finite element coastal ocean modeling and multiscale fluid-particle modeling. |

The project aims to predict the evolution of the radial contraction of stented arteries using a continuum mechanics model, with application to bio-resorbable stent development. The capture of the stress state evolution in the artery wall requires a material model that includes: - the modeling of the main constituents such as collagen, elastin and smooth muscles ; - time dependent evolution such as growth and structural remodeling. Some developed tools are also used to predict fracture in bended stainless steels. |

- Simulating flow and sediment transport in the Lower Mekong River; - Simulating flow in Tonle Sap, Cambodia by SLIM; - Study on floc characteristics in Luang Prabang, Laos and Mekong Delta |

Accounting |

is Full Professor of Applied Mathematics and Mechanics in the Ecole Polytechnique de Louvain. His research topics include the development of mathematical models and numerical tools for predicting the behaviour of complex materials and analysing their forming processes., computational rheology, fluid mechanics, modeling of polymeric solutions and melts, modeling of turbulent flows, computational geometry and design, numerical software engineering, non-linear finite element methods and formulations, error estimation and adaptive numerical methods, parallel computing. |

graduated as materials engineer at Université catholique de Louvain in 2009. Combining both experiments and simulations, his doctoral research focus on the viscoplasticity and the strain localization in metallic thin films. The Lab-on-chip technique is used to characterize the yield stress, the ductility, the hardening behavior and the strain rate sensitivity of Ni thin films. Guerric is also working on the development of a localized necking model dedicated to thin films and nanocrystalline metals which aims at accounting for strain gradient plasticity effects, for grain size dependent strength, rate sensitivity and the possible contribution of creep/relaxation mechanisms. A dislocation-based crystal plasticity model has also been developed in order to study the mechanical and creep/relaxation behavior of the polycrystalline Pd thin films with high initial defect concentration, obtained by M-S Colla during her PhD thesis. |

received her master degree from Tsinghua University (China) and from Ecole Centrale de Lille (France) in 2008. She completed her PhD thesis in 2012 under the supervision of Prof. Dorte Juul Jensen and Prof. Wolfgang Pantleon in the Department of Wind Energy (former Risoe National Laboratory), Technical University of Denmark. Her PhD work focused on the microstructures of nanosized and ultrafine grained metallic materials produced by severe plastic deformation, and the microstructure evolution during recrystallization. She worked on the same laboratory as a postdoctoral researcher until 2015, when she joined UCLouvain as a FNRS postdoctoral researcher. Her postdoctoral research focuses on microstructure evolution in material containing fine-scale twins. She is interested in advanced characterization techniques including: electron backscattered diffraction (EBSD), 3-dimensional X-ray diffraction (3DXRD), diffraction contrast tomography (DCT) and in-situ local strain measurement using digital image correlation (DIC). She is also interested in the crystal plasticity simulation (finite element) of the deformation structure, and simulation of recrystallization. |

obtained a master in mechanical and process engineering at the Institut Catholique des Arts et M?tiers (ICAM) in Toulouse in 2012, followed by a Master in research on fluid dynamics (M2RDET) at Universit? Toulouse III Paul Sabatier (UPS) in 2013, and started his PhD at UCL in the fall of 2013. His PhD aims at devising Vortex Particle Mesh CFD methods (VPM, aslo known as Vortex-in-Cell (VIC)) for use on multiphase flows, with applications in the nuclear industry. VPM methods are known to be very effective for the simulation of wakes, but their capabilities for the simulation of multiphase flows are not currently well known. |

Minimizers of so-called Ginzburg-Landau functionals are functions that minimize both their variations and the passage of their norms to values ??different from 1. The arbitration between the importance of these two elements is done via a parameter epsilon. When epsilon is set to 0, the norm of the minimizers is 1 unless, if necessary, in a finite number of points. The presence of those points (called singular points) depends on the surface considered. The study of Ginzburg-Landau functionals is fashionable. In the context of mesh applications, these functionals are notably used for the construction of the most regular possible cross fields intended to be supports for the construction of quadrangular meshes as regular as possible. In this context, the singular points of minimizers of Ginzburg-Landau functionals can be mapped to singular nodes in the meshes we are trying to construct. Indeed, these meshes pursue the same two objectives as those involved in the Ginzburg-Landau functionals, namely, be as regular as possible and placing singular nodes in an optimized manner if singular nodes are necessary. In the case of non-constant curvature surfaces, the introduction of a covariant gradient can potentially make it possible to construct Ginzburg-Laudau functionals that are more suitable for these surfaces. -Study of a Ginzburg-Landau fonctional containing a co-variant -gradient. -Implementation of mathematical curvature for numerical applications. -Mathematical study of cross fields. |

completed his master in Mechanical Engineering at Université catholique de Louvain in 2016. His master thesis was entitled "GPU Optimization of Spectral Element Method for Shallow Water Equations" He is currently doing a PhD on Multi-threaded Mesh Generation under the supervision of Prof. Jean-François Remacle. His research aims to improve the performance of 3D tetrahedral mesh generation by parallelizing and enhancing state of the art meshing process. |

did her PhD in the RING team from GeoRessources laboratory in Nancy, France, under the supervision of Bruno Lévy and Guillaume Caumon. She was also part of the ALICE team of Loria in Nancy. In September 2014, She joined the WIAS, Berlin, Germany as a post-doctoral researcher, her project was sponsored by Total. In 2015, she received the Computers & Geosciences Best paper of 2014. |

obtained a master in Physics at Université catholique de Louvain. He is currently pursuing a PhD at the frontier between physical climatology and applied mathematics under the supervision of Prof. V. Legat and Prof. T. Fichefet. The aim of his thesis is to improve the representation of fractures in sea ice (leads) in the global ocean-sea ice NEMO-LIM3 model by implementing a Maxwell elasto-brittle rheology in it. |

To automatically build block-structured hexahedral meshes, we generate smooth frame fields which are aligned with the boundary of 3D models and we exploit their geometry and topology to extract block decompositions, which are suited for hexahedral meshing. |

After his Engineering Degree at the University of Liège in Belgium in 1992, Jean-François Remacle obtained in 1997 a Ph.D. from the same University. He then spent two years at the Ecole Polytechnique de Montréal as a post-doctoral fellow of Prof. F. Trochu, followed by three years at Rensselaer Polytechnic Institute in the research team of Prof. M. Shephard (one year as research associate followed by two years as research assistant professor). It was during his stay at Rensselaer that Pr. Remacle started to work closely with Mark Shephard on mesh generation. Pr. Shephard's seminal work on mesh generation is one of the most important contributions ever. It was also during that stay that Pr. Remacle started the development of Gmsh, the open source mesh generator. After these five years in Northern America, Jean-François Remacle joined the Université catholique de Louvain in 2002 as an assistant Professor. He then became Associate Professor in 2005 and Full Professor in 2012. In the following years of his return to Europe, Pr. Remacle dedicated a large part of his research to mesh generation. |

graduated as a civil engineer in applied mathematics from Université catholique de Louvain in 2012 and is presently pursuing a PhD under the supervision of Prof. E. Deleersnijder (UCL/IMMC/MEMA) and Prof. E. Hanert (UCL/ELI/ELIE). The topic of the research is the numerical modelling of the river-to-sea continuum of major rivers (i.e. Congo River and Columbia River). The goal is to study the estuarine and coastal dynamics and their interactions with tides, river discharges and atmospheric/oceanic circulations. This thesis is performed within the framework of the SLIM project (http://sites.uclouvain.be/slim/). |

He completed his master in Computer Science and Engineering at Université catholique de Louvain in 2016. His master thesis was titled "Solving the Maximum Weight Independent Set Problem: Application to Indirect Hex-Mesh Generation". He is currently doing a PhD under the supervision of Prof. Jean-François Remacle. His research focuses on all-hex meshing. |

graduated as a mechanical engineer at Université catholique de Louvain (Belgium) in 2014 and is presently pursuing a PhD under the supervision of Prof. V. Dehant and Prof. E. Deleersnijder. The aim of his thesis is to investigate the tides of Titan liquid bodies. The model SLIM, developed at UCL, is used in order to predict the tidal response of the surface seas and the global subsurface ocean. The investigation includes research on the influence of Titan surface deformations, variation in composition between linked seas, and other poorly constrained parameters. This study will lead to further insights in unexplained phenomena observed by Cassini spacecraft and will be an asset for future exploratory missions. |

The generation of adaptive meshes has been one thriving research area in the last two decades.The generation of adaptive anisotropic meshes allows to dramatically reduce the number of degrees of freedom required to obtain a given accuracy. There is a growing consensus in the computational mechanics community that state of the art solver technology requires, and will continue to require too extensive computational resources to provide the necessary resolution for a broad range of demanding applications, even at the rate that computational power increases. The requirement for high resolution naturally leads us to consider methods which have a higher order of grid convergence than the classical (formal) 2nd order provided by most industrial grade codes. This indicates that higher-order discretization methods will replace at some point the current finite volume and finite element solvers, at least for part of their applications. The development of high-order numerical technologies for engineering analysis has been underway for many years now. For example, Discontinuous Galerkin methods (DGM) have been largely studied in the literature, initially in a theoretical context, and now from the application point of view. In many contributions, it is shown that the accuracy of the method strongly depends on the accuracy of the geometrical discretization. Consequently, it is necessary to address the problem of generating the high- order meshes that are needed to fully benefit from high-order methods. Our team at UCL was one of the pioneers in curvilinear meshing. This research project aims at developing a new area of research, namely curvilinear mesh adaptation. The underlying research question can be stated as follow: let f(x,y) be a smooth function defined on the unit square. What is the mesh that minimizes the approximation error || f - Pf || where || . || is the L2 norm and P the Clément interpolant. Two main questions will have to be addressed: (i) how can we define a suitable metric that actually represents the approximation error and (ii) how do we build a mesh that is somehow aligned with the geodesics of the metric. |

graduated in material science from Ufa State Aviation Technical University (Russia) in 2012 and is presently pursuing a PhD under the joint supervision of Prof. Laurent Delannay and Dr. Dmitry Terentyev (SCK-CEN). The topic of the research is "Finite element modelling of mechanical properties of tungsten under neutron irradiation". The extreme thermal operation conditions and high neutron flux in fusion devices lead to material degradation, however, tungsten, the main candidate for the plasma-facing material, needs to possess high crack resistance and ductility within the operating time. The objective of this project is to develop a finite element model capable to simulate mechanical behaviour of polycrystalline tungsten under tensile testing with the focus made on effect of test temperature and irradiation-induced defects, by drawing information from both experiments and models, such as crystal plasticity, molecular dynamics and dislocation dynamics. The model will be used to predict the mechanical integrity of commercial tungsten grades upon ITER-relevant and DEMO-relevant exploitation conditions accounting for the neutron irradiation and transient loads. |