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A weak formulation of heterogenous viscoacoustic wave propagation in infinite domain

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Earthquake Engineering and Engineering Vibration 2025年第1期24卷 31-51页

作者： Xie Zhinan Zheng Yonglu Paul Cristini Alexis Bottero Shan Zhendong Lu Jianqi Zhang Xubin Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationKey Laboratory of Earthquake Disaster MitigationMinistry of Emergency ManagementHarbin 150080China laboratoire de mecanique et d’Acoustique du CNRS Aix Marseille Univ.CNRSMarseille F-13353France Marine Physical Laboratory Scripps Institution of OceanographyUniversity of CaliforniaSan Diego 92093USA

The accurate simulation of wave propagation in real media requires properly taking the attenuation into account,which leads to wave dissipation together with its causal companion,wave *** this study,to obtain a weak formulation of heterogenous viscoacoustic wave propagation in an infinite domain,the viscoacoustic medium is first characterized by its frequency-dependent complex bulk compliance instead of the classically used complex bulk ***,a mechanical model using serially connected standard linear solids(SSLS)is built to obtain the rational approximation of the complex bulk compliance whose parameters are calculated via an adapted nonlinear optimization *** the obtained bulk compliance-based constitutive relation,a novel second-order viscoacoustic wave equation in the frequency domain is derived,of which the weak formulation can be physically explained as the virtual work equation and can thus be discretized using a continuous spectral element method in ***,a new method is introduced to address the convolution terms involved in the inverse Fourier transform,whose accurate time integration can then be achieved using an explicit time scheme,which avoids the transient growth that exists in the classical *** resulting full time-space decoupling scheme can handle wave propagation in arbitrary heterogeneous ***,to treat the wave propagation in an infinite domain,a perfectly matched layer in weak formulation is derived for the truncation of the infinite domain via complex coordinate stretching of the virtual work *** only minor modification,the resulting perfectly matched layer can be implemented using the same time scheme as for the wave equation inside the truncated *** accuracy,numerical stability,and versatility of the new proposed scheme are demonstrated with numerical examples.

关键词： viscoacoustic wave standard linear solid complex bulk compliance heterogenous media perfectly matched layer Legendre spectral element method

Rotating instability in the vaneless diffuser of a radial flow pump

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Journal of Thermal Science 2008年第4期17卷 368-374页

作者： A.Dazin O.Coutier-delgosha P.Dupont S.Coudert G.Caignaert G.Bois laboratoire de Mécanique de lille(UMR CNRS 8107) Arts et Métiers ParisTech laboratoire de Mécanique de lille Ecole Centrale de Lille laboratoire de Mécanique de lille CNRS

The paper refers to the behavior of a vaneless diffuser of a radial flow pump in partial flow operating conditions. Some experimental data have been obtained using 2D/2C PIV and unsteady pressure measurements within the diffuser, in various operating conditions. The experimental results at the lower flow rate are compared with two-dimensional numerical calculations.

关键词： Vaneless diffuser Radial flow pump Instability Particle Image Velocimetry Pressure measurements 2D calculations.

Mechanical Properties of Soil-Rock Mixture Filling in Fault Zone Based on Mesostructure

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Computer Modeling in Engineering & Sciences 2022年第8期132卷 681-705页

作者： Mei Tao Qingwen Ren Hanbing Bian Maosen Cao Yun Jia department of Engineering Mechanics Hohai UniversityNanjing210098China laboratoire de Genie Civil et g´eo-Environnement Universite de LilleLille59000France laboratoire de mecanique MultiphysiqueMulti-´echelleUniversite de LilleLille59000France

Soil-rock mixture(SRM)filling in fault zone is an inhomogeneous geomaterial,which is composed of soil and rock *** controls the deformation and stability of the abutment and dam foundation,and threatens the long-term safety of high arch *** study the macroscopic and mesoscopic mechanical properties of SRM,the development of a viable mesoscopic numerical simulation method with a mesoscopic model generation technology,and a reasonable parametric model is crucially desired to overcome the limitations of experimental conditions,specimen dimensions,and experiment *** this end,this study presents a mesoscopic numerical method for simulating the mechanical behavior of SRM by proposing mesoscopic model generation technology based on its mesostructure features,and a rock parameter model considering size *** validity and rationality of the presented mesoscopic numerical method is experimentally verified by the triaxial compression tests with different rock block contents(RBC).The results indicate that the rock block can increase the strength of SRM,and it is proved that the random generation technique and the rock parameter model considering size effect are ***,there are multiple failure surfaces for inhomogeneous geomaterial of SRM,and the angle of the failure zone is no longer 45◦.The yielding zones of the specimen are more likely to occur in thin sections of soil matrix isolated by blocks with the failure path avoiding the rock *** proposed numerical method is effective to investigate the meso-damage mechanism of SRM.

关键词： Soil-rock mixture(SRM) triaxial compression tests random generation technique mesostructure rock parameter model size effect finite element method

Recent progress in augmenting turbulence models with physics-informed machine learning

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Journal of Hydrodynamics 2019年第6期31卷 1153-1158页

作者： Xinlei Zhang Jinlong Wu Olivier Coutier-delgosha Heng Xiao Kevin T.Crofton department of Aerospace and Ocean Engineering Virginia TechBlacksburgVirginiaUSA laboratoire de mecanique des Fluides de lille一Kampe de Feriet Arts et Metiers ParisTechLilleFrance

In view of the long stagnation in traditional turbulence modeling,researchers have attempted using machine learning to augment turbulence *** paper presents some of the recent progresses in our group on augmenting turbulence models with physics-informed machine *** also discuss our works on ensemble-based field inversion to provide training data for constructing machine learning *** and on-going research efforts are introduced.

关键词： Machine learning turbulence modeling data-driven modeling model uncertainty

Tribological Behavior of CoCr28Mo/CoCr28Mo Pair in the Presence of Bio-lubrication

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Journal of Bionic Engineering 2018年第4期15卷 703-712页

作者： Manel Guezmil Walid Bensalah Salah Mezlini laboratoire de Genie mecanique (LGM) ENIM Rue Ibn Eljazzar 5019 Monastir University Tunisia

The tribological behavior of the CoCr28Mo/CoCr28Mo pair was studied using pin-on-disc tribometer. Four bio-lubricants were re- tained including pure sesame oil, nigella oil, physiological solution （0.9% NaC1） and Hyalgan. Hyalgan is a sodium hyaluronate （20 mg/2 mL） pharmaceutical intra-articular injection used, in this study, as a reference. The Coefficient of Friction （CoF） and wear rate （K） of CoCr28Mo were computed after tribological tests. The tribological efficiency of vegetable oils with regard to their chemical compo- sition and structure was compared to Hyalgan. It is found that, the use of vegetable oils enhanced significantly the tribological behavior of CoCr28Mo/CoCr28Mo pair. The obtained results were correlated to the chemical structure of vegetable oils namely the Unsaturations Number （UN） of fatty acids constituting the oil. Microscopic and chemical characterization of CoCr28Mo pins and discs were conducted and the wear mechanism was discussed.

关键词： CoCr alloy friction coefficient wear resistance oil lubrication

Influence of soil saturation on the free field response of liquefiable soils

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Underground Space 2017年第1期2卷 30-37页

作者： Hanbing Bian Isam Shahrour Yun Jia department of Geotechnical Engineering School of Civil EngineeringTongji UniversityShanghai 200092China LEM3 UMR CNRS 7239 Universite de LorraineIle du Saulcy57045 MetzFrance laboratoire de Genie Civil et geo-Environnement Universite de Lille59650 Villeneuve d’AscqFrance laboratoire de mecanique de lille Universitede Lille59650 Villeneuve d’AscqFrance

The present paper presents analysis of the influence of the soil saturation on the free-field response of liquefiable *** are conducted using a finite element program developed for partially saturated soils subjected to cyclic *** performances of the proposed model are analysed by simulation of undrained triaxial tests with different water *** finite element program is then used for the analysis of the influences of the soil saturation,density and position of the water table on the liquefaction of a soil layer subjected to cyclic *** show that the soil saturation significantly affects the liquefaction of partially saturated sandy *** decrease in the soil saturation results in a reduction of liquefaction risk.

关键词： Free field Liquefaction Dynamic Cyclic loading Seismic Numerical

Unsteady Rotor-Stator Interaction in High Speed Compressor and Turbine Stages

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Journal of Thermal Science 2005年第4期14卷 289-297页

作者： I.Trébinjac D.Charbonnier F.Leboeuf Ecole Centrale de Lyon Laboratoire de Mecanique des Fluides et d'AcoustiqueUMR CNRS 550969134 Ecully CedexFrance

The blade row interaction can alter the time-mean flow and therefore be of interest for aerodynamic design analysis. Whereas results within low subsonic turbomachines are quite numerous in the literature, there have been far fewer works which give results of blade row interaction within high speed cases. Two cases are related in this paper. First, the effects of an incoming wake on the rotor flow field of a transonic compressor are analyzed. The blade row interaction proved to be positive regarding the total pressure ratio, but negative regarding the losses. The second case concerns a transonic turbine. Particular emphasis is placed on the assessment of the deterministic correlations included in the Averaged Passage Equation System.

关键词： unsteady aerodynamics rotor stator interaction deterministic stress.

Assessment of Linear and Non-Linear Two-Equation Turbulence Models for Aerothermal Turbomachinery Flows

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Journal of Thermal Science 2006年第1期15卷 14-26页

作者： Pascale KULISA Cedric DANO laboratoire de mecanique des Fluides et d'Acoustique UMR5509 Ecole Centrale de Lyon 69134 ECULLY Cedex France

Three linear two-equation turbulence models k- ε, k- ω and k- 1 and a non-linear k- 1 model are used for aerodynamic and thermal turbine flow prediction. The pressure profile in the wake and the heat transfer coefficient on the blade are compared with experimental data. Good agreement is obtained with the linear k-1 model. No significant modifications are observed with the non-linear model. The balance of transport equation terms in the blade wake is also presented. Linear and non-linear k - 1 models are evaluated to predict the threedimensional vortices characterising the turbine flows. The simulations show that the passage vortex is the main origin of the losses.

关键词： turbulence model numerical simulation turbomachinery.

Tribological Investigation of HDPE-cuttlebone and HDPE-red Coral Composites

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Journal of Bionic Engineering 2019年第6期16卷 1068-1079页

作者： Amira Salem Walid Bensalah Salah Mezlini Universite de Monastir Ecole Nationale d'Ingenieurs de Monastir(ENIM)Laboratoire de Genie Mecanique(LGM)LR99ES325019MonastirTunisia

In this paper,the tribological properties of cuttlebone(CB)-reinforced high density polyethylene(HDPE)and Red Coral(RC)-reinfbrced HDPE composites were *** composite specimens were prepared with a hot compression molding machine using different weight proportions of fillers blended with *** tribological behavior of the composite disks was studied using pin-on-disk tribometer under dry condition against stainless steel M30NW *** coefficient of friction as well as wear rate were examined to study the effects of the two fillers on the tribological perfonnance of both *** wear tests,different composites were examined using a Scanning Electron Microscope(SEM).It was fbund that the use of cuttlebone(CB)and Red Coral(RC)as reinforcement improved the tribological properties of HDPE.

关键词： cuttlebone-reinforced HDPE red coral-reinforced HDPE wear rate friction coefficient wear mechanism