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arXiv 2018年

作者： Kooij, Gijs L. Botchev, Mikhail A. Frederix, Edo M.A. Geurts, Bernard J. Horn, Susanne Lohse, Detlef Van Der Poel, Erwin P. Shishkina, Olga Stevens, Richard J.A.M. Verzicco, Roberto Multiscale Modeling and Simulation Faculty EEMCS University of Twente Enschede Netherlands Applied Mathematics and Mathematical Physics Imperial College London Physics of Fluids Faculty of Science and Technology University of Twente Enschede Netherlands Mathematics of Computational Science Faculty EEMCS University of Twente Enschede Netherlands Keldysh Institute of Applied Mathematics Russian Academy of Sciences Moscow Russia Max Planck Institute for Dynamics and Self-Organization Göttingen Germany Dipartimento di Ingegneria Meccanica Università di Roma Tor Vergata Rome Italy Faculty of Applied Physics Fluid Dynamics Laboratory Eindhoven University of Technology Eindhoven Netherlands Earth Planetary and Space Sciences University of California Los Angeles United States

Computational codes for direct numerical simulations of Rayleigh-Bénard (RB) convection are compared in terms of computational cost and quality of the solution. As a benchmark case, RB convection at Ra = 108and Pr = 1 in a periodic domain, in cubic and cylindrical containers is considered. A dedicated second-order finite-difference code (AFID/RBflow) and a specialized fourth-order finite-volume code (Goldfish) are compared with a general purpose finite-volume approach (OpenFOAM) and a general purpose spectral-element code (Nek5000). Reassuringly, all codes provide predictions of the average heat transfer that converge to the same values. The computational costs, however, are found to differ considerably. The specialized codes AFID/RBflow and Goldfish are found to excel in efficiency, outperforming the general purpose flow solvers Nek5000 and OpenFOAM by an order of magnitude with an error on the Nusselt number Nu below 5%. However, we find that Nu alone is not sufficient to assess the quality of the numerical results: in fact, instantaneous snapshots of the temperature field from a near wall region obtained for deliberately under-resolved simulations using Nek5000 clearly indicate inadequate flow resolution even when Nu is converged. Overall, dedicated special purpose codes for RB convection are found to be more efficient than general purpose codes. Copyright © 2018, The Authors. All rights reserved.

关键词： Direct numerical simulation

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Free-surface flow simulations for moored and floating offshore platforms 7

Free-surface flow simulations for moored and floating offsho...

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7th European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS Congress 2016

作者： Veldman, Arthur E.P. Luppes, Roel Van Der Plas, Peter Van Der Heiden, Henri Düz, Bülent Seubers, Henk Helder, Joop Bunnik, Tim Huijsmans, René Institute for Mathematics and Computer Science University of Groningen Groningen Netherlands Department of Ship Hydrodynamis Delft University of Technology Delft Netherlands Maritime Reseach Institute MARIN Wageningen Netherlands Multiscale Modeling and Simulation University of Twente Enschede Netherlands

ISBN: (纸本)9786188284401

During the development of the ComFLOW simulation method many challenges have to be tackled concerning the flow modelling and the numerical solution algorithm. Examples here of are wave propagation, absorbing boundary conditions, fluid-solid body interaction, turbulence modeling and numerical efficiency. Some of these challenges will be discussed in the paper, in particular the design of absorbing boundary conditions and the numerical coupling for fluid-solid body interaction. As a demonstration of the progress made, a number of simulation results for engineering applications from the offshore industry will be presented: a wave-making oscillating buoy, a free-fall life boat dropping into wavy water, and wave impact against a semi-submersible offshore platform. For those applications, MARIN has carried out several validation experiments.

关键词： Computational fluid dynamics

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A quantitative ultrasound method to estimate dental implant stability

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The Journal of the Acoustical Society of America 2017年第5_SUPPLEMENT期141卷 3887-3887页

作者： Romain Vayron Vu-Hieu Nguyen Romain Bosc Guillaume Haiat Multiscale Modeling and Simulation Lab. CNRS Créteil France Multiscale Modeling and Simulation Lab. CNRS Creteil France Université Paris-Est Créteil INSERM U955 IMRB Creteil France Multiscale Modeling and Simulation Lab. CNRS Laboratoire MSMS Faculté des Sci. UPEC 61 Ave. du gal de Gaulle Creteil 94010 France guillaume.haiat@univ-paris-est.fr

Dental implants are widely used clinically. However, implant failures, which may have dramatic consequences, still occur and remain difficult to anticipate. Accurate measurements of implants biomechanical stability are of interest since they could be used to improve the surgical strategy. The aim of this paper is to determine whether quantitative ultrasound can be used to determine dental implant stability. Firstly, an implant was initially completely inserted in the proximal part of a bovine humeral bone sample. The 10 MHz ultrasonic response of the implant was then measured and a quantitative indicator was derived. Then, the implant was unscrewed by 2π radians and the measurement was realized again. The value of indicator significantly increases as a function of the number of rotation. The results show that bone quantity in contact with the implant has a significant influence on its ultrasonic response. Secondly, a 3D finite element model was employed and the geometrical configuration was assumed to be axisymmetric. The numerical results show that the implant ultrasonic response changes significantly when a liquid layer is located at the implant interface. This study paves the way for the development of an ultrasonic tool to be used for the monitoring of osseointegration.

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Wannier90 as a community code: New features and applications

arXiv

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arXiv 2019年

作者： Pizzi, Giovanni Vitale, Valerio Arita, Ryotaro Blugel, Stefan Freimuth, Frank Geranton, Guillaume Gibertini, Marco Gresch, Dominik Johnson, Charles Koretsune, Takashi Ibanez-Azpiroz, Julen Lee, Hyungjun Lihm, Jae-Mo Marchand, Daniel Marrazzo, Antimo Mokrousov, Yuriy Mustafa, Jamal I. Nohara, Yoshiro Nomura, Yusuke Paulatto, Lorenzo Ponce, Samuel Ponweiser, Thomas Qiao, Junfeng Thole, Florian Tsirkin, Stepan S. Wierzbowska, Malgorzata Marzari, Nicola Vanderbilt, David Souza, Ivo Mosto, Arash A. Yates, Jonathan R. Theory and Simulation of Materials National Centre for Computational Design and Discovery of Novel Materials Ecole Polytechnique Federale de Lausanne LausanneCH-1015 Cavendish Laboratory Department of Physics University of Cambridge CambridgeCB30HE Departments of Materials and Physics Thomas Young Centre for Theory and Simulation of Materials Imperial College London LondonSW72AZ RIKEN Center for Emergent Matter Science 2-1 Hirosawa Wako Saitama351-0198 Department of Applied Physics University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Peter Grunberg Institut Institute for Advanced Simulation JARA Julich52425 Department of Quantum Matter Physics University of Geneva Geneva ETH Zurich Zurich Departments of Materials and Physics Imperial College London LondonSW72AZ Department of Physics Tohoku University Sendai JST PRESTO Kawaguchi Saitama Centro de Fisica de Materiales Universidad Del Pais Vasco San SebastianE-20018 Institute of Physics Ecole Polytechnique Federale de Lausanne LausanneCH-1015 Korea Institute for Advanced Study Hoegiro 85 Seoul02455 Department of Physics Center for Theoretical Physics Seoul National University Seoul08826 Laboratory for Multiscale Mechanics Modeling Ecole Polytechnique Federale de Lausanne Lausanne Institute of Physics Jonannes-Gutenberg University of Mainz Mainz55099 Department of Physics University of California BerkeleyCA94720 United States ASMS Co. Ltd. 1-7-11 Higashi-Gotanda Shinagawa-ku Tokyo141-0022 Institut de Mineralogie de Physique des Materiaux et de Cosmochimie Sorbonne Universite CNRS Case 115 4 place Jussieu Paris Cedex75252 Department of Materials University of Oxford Parks Road OxfordOX13PH Research Institute for Symbolic Computation Johannes Kepler University Altenberger Strae 69 Linz4040 Fert Beijing Institute School of Microelectronics BDBC Beihang University Beijing Materials Theory ETH Zurich Wolfgang-Pauli-Strasse 27 ZurichCH-8093 Department of Physics University of Zurich

Wannier90 is an open-source computer program for calculating maximally-localised Wannier functions (MLWFs) from a set of Bloch states. It is interfaced to many widely used electronicstructure codes thanks to its independence from the basis sets representing these Bloch states. In the past few years the development of Wannier90 has transitioned to a community-driven model;this has resulted in a number of new developments that have been recently released in Wannier90 v3.0. In this article we describe these new functionalities, that include the implementation of new features for wannierisation and disentanglement (symmetry-adapted Wannier functions, selectivelylocalised Wannier functions, selected columns of the density matrix) and the ability to calculate new properties (shift currents and Berry-curvature dipole, and a new interface to many-body perturbation theory);performance improvements, including parallelisation of the core code;enhancements in functionality (support for spinor-valued Wannier functions, more accurate methods to interpolate quantities in the Brillouin zone);improved usability (improved plotting routines, integration with high-throughput automation frameworks), as well as the implementation of modern software engineering practices (unit testing, continuous integration, and automatic source-code documentation). These new features, capabilities, and code development model aim to further sustain and expand the community uptake and range of applicability, that nowadays spans complex and accurate dielectric, electronic, magnetic, optical, topological and transport properties of materials. Copyright © 2019, The Authors. All rights reserved.

关键词： Open source software

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Determination of the acetabular cup implant stability using an acoustic method based on the impact between the hammer and the ancillary

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The Journal of the Acoustical Society of America 2017年第5_SUPPLEMENT期141卷 3831-3831页

作者： Giuseppe Rosi Vu-Hieu Nguyen Antoine Tijou Romain Bosc Guillaume Haiat Multiscale Modeling and Simulation Lab. CNRS Creteil France Université Paris-Est Créteil INSERM U955 IMRB Creteil France Multiscale Modeling and Simulation Lab. CNRS Laboratoire MSMS Faculté des Sci. UPEC 61 Ave. du gal de Gaulle Creteil 94010 France guillaume.haiat@univ-paris-est.fr

The hemispherical acetabular cup (AC) implant is used during total hip replacement surgery and is inserted in the acetabulum using impacts applied with an orthopedic hammer. However, the assessment of the AC implant primary stability remains difficult. The aim of this study was to investigate the feasibility of retrieving the AC implant stability based on impact signal analyses. AC implants with various sizes were inserted in 12 cadaveric hips following the same protocol as the one employed in the clinic. An instrumented hammer was then used to measure the variation of the force as a function of time produced during the impact between the hammer and the ancillary. Then, an indicator I was determined for each impact based on the impact momentum. A significant correlation (R² = 0.69) was found between I and the pull-out force. Moreover, a tridimensional axisymmetric finite element model was developed to simulate the insertion processes of the AC implant into bone tissue during impacts. The variation of the force applied between the hammer and the ancillary was analyzed and the numerical results were compared with the experimental results. The results show the potential of impact analysis to retrieve the bone-implant contact properties.

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Assessment of dental implant stability: Coupling modeling and experimental approaches

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The Journal of the Acoustical Society of America 2017年第4_SUPPLEMENT期142卷 2566-2566页

作者： Romain Vayron Vu-Hieu Nguyen Guillaume Haiat Multiscale Modeling and Simulation Lab. CNRS Laboratoire MSMS Faculté des Sci. UPEC 61 Ave. du gal de Gaulle Creteil 94010 France guillaume.haiat@univ-paris-est.fr

Dental implants are widely used clinically but implant failures, which may have dramatic consequences, still occur and remain difficult to anticipate. Accurate measurements of implants biomechanical stability are of interest since they could be used to improve the surgical strategy. The aim of this work is to develop a medical device capable of estimating dental implant stability using quantitative ultrasound. To do so, our approach consists in coupling modeling and experimental methods. Firstly, an implant was initially completely inserted in the proximal part of a bovine humeral bone sample. The 10 MHz ultrasonic response of the implant is then measured and a quantitative indicator is derived. Then, the implant is unscrewed by 2π radians and the measurement was realized again. The value of indicator significantly increases as a function of the number of rotation. The results show that bone quantity in contact with the implant has a significant influence on its ultrasonic response. Secondly, a 3D finite element model is employed and the geometrical configuration is assumed to be axisymmetric. The numerical results show that the implant ultrasonic response changes significantly when a liquid layer is located at the implant interface.

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Direct Numerical simulation of biomass pyrolysis and combustion with gas phase reactions

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Journal of Physics: Conference Series 2016年第3期745卷

作者： A. Awasthi J. G. M. Kuerten B. J. Geurts Department of Mechanical Engineering Eindhoven University of Technology Eindhoven The Netherlands Multiscale Modeling and Simulation Faculty EEMCS University of Twente Enschede The Netherlands Anisotropic Turbulence Department of Applied Physics Eindhoven University of Technology Eindhoven The Netherlands

We present Direct Numerical simulation of biomass pyrolysis and combustion in a turbulent channel flow. The model includes simplified models for biomass pyrolysis and char combustion along with a model for particle tracking. The gas phase is modelled as a mixture of reacting gas species. The gas-particle interactions for mass, momentum, and energy exchange are included by two-way coupling terms. The effect of two-way coupling on the conversion time of biomass particles is found noticeable for particle volume fractions > 10-5. We also observe that at constant volume fraction the effect of two-way coupling increases as the particle size is reduced, due to the higher total heat exchange area in case of smaller particles. The inclusion of gas phase homogeneous reactions in the DNS model decreases the biomass pyrolysis time due to higher gas temperatures. In contrast, including gas phase reactions increases the combustion time of biomass due to the lower concentration of oxygen at the particle surface.

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Acoustical estimation of endosseous implant stability: Finite element modeling and experimental validation

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The Journal of the Acoustical Society of America 2016年第4_SUPPLEMENT期140卷 3191-3191页

作者： Vu-Hieu Nguyen Romain Vayron Guillaume Haiat Multiscale Modeling and Simulation Lab. CNRS Laboratoire MSME UMR 8208 fac des Sci. UPEC 61 av du gal de Gaulle Creteil France vu-hieu.nguyen@u-pec.fr

Various endosseous implants are widely used in orthopedic and dental surgeries. However, failures are observed, which may have dramatic consequences and are often due to a loss of implant stability. The aim of this presentation is to describe two acoustical methods developed to assess the stability of different implants. First, a quantitative ultrasound method was used to determine the stability of dental implants. A monoelement 10 MHz transducer is screwed into the implant and the signal is processed to obtain an indicator. The method was first validated in implants embedded in biomaterials used as bone substitutes, then in vitro and eventually in vivo by comparison with histology. A 3D FEM was developed to optimize the device conception and carry out sensitivity studies. Second, an impact hammer was used in order to investigate whether the AC implant primary stability can be evaluated using such approach. The method was first validated in vitro and in cadaveric experiments. The results showed that an indicator based on the impact momentum may be correlated to the implant pull-out force. A 3D FEM was also developed to analyze and better understand experimental results. This study shows the potential of acoustical methods to assess non-invasively implant stability.

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Quantitative ultrasound measurements in trabecular bone using the echographic response of a metallic pin: Application to spine surgery

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The Journal of the Acoustical Society of America 2015年第3_SUPPLEMENT期138卷 1798-1798页

作者： Guillaume Haiat Yoshiki Nagatani Seraphin Guipieri Didier Geiger Multiscale Modeling and Simulation Lab. CNRS Laboratoire MSMS Faculté des Sci. UPEC 61 Ave. du gal de Gaulle Creteil 94010 France guillaume.haiat@univ-paris-est.fr Kobe City College of Technol. Kobe Japan Multiscale modeling and simulation Lab. CNRS Creteil France

Bone quality is an important parameter in spine surgery, but it remains difficult to be assessed clinically. The aim of this work is to demonstrate the feasibility of a QUS method to retrieve bone mechanical properties using an echographic technique taking advantage of the presence of a metallic pin inserted in bone tissue. To do so, an experimental validation is performed and acoustical modeling is used in order to assess the influence of experimental errors. A metallic pin was inserted in bone tissue perpendicularly to the transducer axis. The echographic response of the bone sample was determined and the echoes of the pin inserted in bone tissue and in water were compared to determine speed of sound (SOS) and broadband ultrasonic attenuation (BUA), which was compared to bone volume fraction (BV/TV). A 2-D finite element model was developed to assess the effect of positioning errors. Moreover, the coupling of finite difference time domain simulation with high resolution imaging technique was used to understand the interaction between an ultrasonic wave and the bone microstructure. A significant correlation between SOS and BV/TV was found (R² = 0.6). The numerical results show the relative robustness of the measurement method, which could be useful to estimate bone quality intraoperatively.

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Assessing dental implant stability using quantitative ultrasound methods: Experimental approach and numerical validation

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The Journal of the Acoustical Society of America 2015年第3_SUPPLEMENT期138卷 1799-1799页

作者： Romain Vayron Guillaume Haiat Multiscale Modeling and Simulation Lab. CNRS Laboratoire MSMS Faculté des Sci. UPEC 61 Ave. du gal de Gaulle Creteil 94010 France guillaume.haiat@univ-paris-est.fr

Dental implants are widely used for oral rehabilitation. However, there remain risks of failure that are difficult to anticipate. The objective of this study is to investigate the potentiality of quantitative ultrasound (QUS) to assess dental implant implant stability. To do so, the implant is initially completely inserted in the proximal part of a bovine humeral bone sample. The 10 MHz ultrasonic response of the implant is then measured and a quantitative indicator I is derived based on the rf signal obtained. Then, the implant is unscrewed by 2π radians and the measurement is realized again. The procedure is repeated seven times and the indicator is derived after each rotation of the implant. Analysis of variance (ANOVA) (p < 10−5) tests revealed a significant effect of the amount of bone in contact with the implant on the distribution of I. In parallel, a finite element model is developed in order to model the ultrasonic propagation in the implant surrounded by bone tissue. The results show the feasibility of our QUS device to assess implant primary stability. A good agreement is obtained between experimental and numerical results. This study paves the way for the development of a new approach in oral implantology.

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