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numerical prediction of oceanic mesoscale circulation and satellite altimetry data assimilation in the Western Pacific

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Science China Earth Sciences 2025年第3期68卷 909-927页

作者： Zhijin LI Jianfang FEI Renhe ZHANG Xingliang JIANG Wenlong MA Xiaoping CHENG Lei LIU Guihua WANG Changlin CHEN Department of Atmospheric and Oceanic Sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China Shanghai Key Laboratory of Ocean-land-atmosphere Boundary Dynamics and Climate Change Shanghai 200438China College of Meteorology and Oceanology National University of Defense TechnologyChangsha 410073China

Oceanic mesoscale circulations, primarily manifesting as eddies, typically span around 100 km horizontally and persist for about a month. These circulations represent the main component of oceanic kinetic energy and are referred to as the“weather” of the ocean. Forecasting efforts, focused on periods from a day to a month, target these mesoscale *** in eddy-resolving models, observing systems such as Argo floats and satellite altimeters, and data assimilation techniques have enabled systems like HYCOM in the United States and Mercator-Ocean in Europe to predict these features effectively. To further enhance mesoscale forecasting, the Pacific Regional Ocean Forecast System(RPOFS) was developed for the pan-western Pacific(100°E–178°E, 20°S–50°N). Covering the dynamic Kuroshio and Kuroshio Extension regions, RPOFS features a 3 km horizontal grid and 67 vertical levels, with a multi-scale three-dimensional variational data assimilation(MS-3DVAR) scheme implemented. This system assimilates data from various sources, including satellite sea surface height and temperature, as well as subsurface profiles. In particular, an enhanced altimeter data assimilation methodology allows explicitly constraining both barotropic and baroclinic components of sea surface height. RPOFS demonstrates reliable forecasting of mesoscale circulations, with five-day forecasts accurately predicting eddies larger than 150 km and capturing features of the Kuroshio large meander. Forecasting errors are comparable to or smaller than those of HYCOM and Mercator-Ocean systems.

关键词： Western Pacific Ocean Ocean model Mesoscale eddy numerical prediction Multiscale data assimilation Satellite altimetry

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numerical prediction of the Effect of Laser Shock Peening on Residual Stress and Fatigue Life of Ti-6Al-4V Titanium Alloy

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MATERIALS 2022年第16期15卷 5503-5503页

作者： Ouyang, Peixuan Luo, Xuekun Dong, Zhichao Zhang, Shuting North China Univ Technol Sch Mech & Mat Engn Beijing 100144 Peoples R China AECC Beijing Inst Aeronaut Mat Beijing 100095 Peoples R China

Laser shock peening (LSP) is a promising surface strengthening technology to improve the fatigue life of alloy components. In this work, the residual stress field of Ti-6Al-4V titanium alloy induced by LSP was simulated based on finite element method (FEM), and then the fatigue lives of the non-LSP and LSP-treated specimens subjected to four-point bending were predicted using the software Fe-safe. The simulation results were compared and validated with the corresponding experimental results. LSP treatment produces a maximum compressive residual stress (CRS) of up to 800 MPa on the surface of the specimen and a CRS layer with a thickness of 0.623 mm under the upper surface of the specimen. The existence of the CRS layer reduces the maximum principal stress from 608 MPa to 540 MPa and changes its location from the upper surface into the internal position at a depth of about 0.6 mm during the four-point bending process. This results in experimental and predicted fatigue lives 4.2 and 17.24 times longer for the specimens with LSP pretreatment compared to those without LSP.

关键词： laser shock peening fatigue life four-point bend compressive residual stress numerical prediction

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numerical prediction of solid-liquid slurry flows and derivation of simulation-based correlations for local solid concentration

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PROGRESS IN COMPUTATIONAL FLUID DYNAMICS 2022年第5期22卷 303-316页

作者： Gopaliya, Manoj Kumar Kaushal, Deo Raj CV Raman Global Univ Dept Mech Engn Bhubaneswar Odisha India Indian Inst Technol Delhi Dept Civil Engn New Delhi India

This paper presents correlations for predicting local solid concentration for pseudo-homogeneous and mildly heterogeneous solid-liquid slurry flows through horizontal pipelines using curve fitting techniques applied on exhaustive simulation data. These data are obtained using a duly validated Eulerian multiphase model whose applicability is ascertained for the slurry flow cases under consideration. The ranges of geometric and working input parameters of solid-liquid slurry flow analysed during the present research work are quite comprehensive and wide which increases the applicability realm of the derived correlations. These correlations are also verified against a new set of slurry flow cases and ascertained their accuracy.

关键词： local solid concentration slurry flows simulations computational fluid dynamics CFD pipeline numerical prediction curve fitting contours multiphase flows Eulerian model correlations

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numerical prediction of spatio-temporal frosting patterns of curved surface considering varying working parameters

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Energy Storage and Saving 2023年第1期2卷 348-358页

作者： Xue Liu Xiaojun Dong Shaohang Yan Yu Hou Tianwei Lai State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China

Accurate numerical prediction of frosting patterns is essential for the efficient layout and timing defrosting of heat exchangers under frosting *** this study,a numerical model is developed to predict the spatio-temporal frosting habits on curved surfaces in combination with the correlations of frost density and thermal *** the model,frost melting is *** verification,the frosting and heat transfer characteristics along the flow path are investigated under various structural and operating *** thickness along the path is mainly affected by the cooling surface temperature,while the heat and mass transfer rates are strongly correlated with the humidity *** proportions of latent heat and sensible heat are distributed more unevenly in parallel flow case than in counter flow *** deposition is facilitated by a smaller radius of curvature of the cooling *** uniform frosting characteristics along the path and smaller heat transfer obstruction are presented with a smaller length-to-height ratio of the flow path.

关键词： Frosting numerical prediction Heat transfer Curved surface Varying parameter

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numerical prediction of the spray from an air-assisted fuel injection system via Eulerian-Lagrangian approach

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ENERGY REPORTS 2021年 7卷 6718-6732页

作者： Du, Bingxuan Zhao, Zhenfeng Beijing Inst Technol Sch Mech Engn Beijing 100081 Peoples R China

Air-assisted fuel injection (AAFI) systems may be installed in aviation piston engines for atomization of heavy fuels. However, there are few studies on the in-cylinder air-assisted spray characteristics, which affects the improvement of AAFI engine performance. In this study, an improved air-assisted spray simulation method based on ANSYS FLUENT was proposed to predict the changes in air-assisted spray characteristics alongside spray development, compared with previous simulations, the simulation in this paper was extended in both temporal and spatial domains and more accurate boundary conditions were given. The Eulerian-Lagrangian approach was used to represent the two-phase spray flow and a dynamic mesh model was used to simulate the movement of injector needle valve. The improved method was validated by comparison against experimental results in terms of spray shape, spray volume, spray penetration, spray droplet size spatial distribution, and overall Sauter mean diameter (SMD). By using the improved method, the average relative errors of the simulation results in spray volume and spray penetration were reduced by 13.5% and 10.2%, respectively. Additionally, some typical spray field parameters (gas phase pressure, gasified fuel mass fraction, etc.) were analyzed. The improved method can be used to study the in-cylinder air-assisted spray characteristics, which is beneficial for the fuel injection parameter optimization and the combustion chamber design of the AAFI engine. (C) 2021 The Authors. Published by Elsevier Ltd.

关键词： Air-assisted spray numerical prediction Eulerian-Lagrangian approach Dynamic mesh model

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numerical prediction on frictional characteristics of binary mixtures consisting of flexible cylindrical particles and rigid spheres

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POWDER TECHNOLOGY 2024年 447卷

作者： Zhu, Yanping Mu, Xiwen Guo, Pengyue Zhang, Hao An, Xizhong Jiang, Shengqiang Northeastern Univ Sch Met Key Lab Ecol Met Multimet Mineral Minist Educ Shenyang 110819 Liaoning Peoples R China Minist Educ Engn Res Ctr Frontier Technol Low Carbon Steelmaki Shenyang 110819 Liaoning Peoples R China Inst Low Carbon Frontier Technol Steelmaking Shenyang 110819 Liaoning Peoples R China Xiangtan Univ Sch Mech Engn & Mech Xiangtan 411105 Peoples R China

A Discrete Element Method (DEM) model for deformable cylindrical particles is established to investigate the Jenike shear process of binary mixtures consisting of flexible cylindrical particles and rigid spheres. The effects of the shape of flexible cylindrical particles and the proportion of cylindrical particles to spherical ones on the friction behavior of the mixture are discussed. numerical results show that both the shear stress and internal friction angle increase with the aspect ratio (Ar) of the flexible cylindrical particles but decrease with the increase of the proportion of spherical particles. The role of Ar becomes slight when when the amount of spheres are much higher than the cylindrical particles (double or higher). For the mono-system containing flexible cylindrical particles of Ar=6 but without spheres, the strong interlocking packing structure leads to high shear stress and internal friction angle. It is indicated that the inclusion of rigid spheres disrupts the interlocking structure between flexible cylindrical particles and acts as a lubricant during the shear process. Based on the numerical results, a predictive correlation is established to predict the frictional characteristics of binary mixtures consisting of flexible cylindrical particles and rigid spheres considering the effect of particle shape and proportion. Furthermore, through a microscopic analysis of the numerical results, a deeper understanding of this phenomenon is gained. It is confirmed that the spherical particles can fill the voids between the flexible cylindrical particles, increasing the compactness of the mixture and promoting lubrication effects. The current research contributes to the better understanding of the mechanism of particle flow and is of paramount importance to improve the kinetic theories for complex granular flows.

关键词： numerical prediction Frictional characteristic Binary mixture Flexible cylindrical particle

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Step-by-Step numerical prediction of Aerodynamic Noise Generated by High Speed Trains

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Chinese Journal of Mechanical Engineering 2022年第2期35卷 251-264页

作者： Tian Li Deng Qin Ning Zhou Weihua Zhang State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China

In this paper,the unsteady flow around a high-speed train is numerically simulated by detached eddy simulation method(DES),and the far-field noise is predicted using the Ffowcs Williams-Hawkings(FW-H)acoustic *** reliability of the numerical calculation is verified by wind tunnel *** superposition relationship between the far-field radiated noise of the local aerodynamic noise sources of the high-speed train and the whole noise source is *** the aerodynamic noise of high-speed trains is derived from its different components,a stepwise calculation method is proposed to predict the aerodynamic noise of high-speed *** results show that the local noise sources of high-speed trains and the whole noise source conform to the principle of sound source energy *** the head,middle and tail cars of the high-speed train as noise sources,different numerical models are established to obtain the far-field radiated noise of each aerodynamic noise *** far-field total noise of high-speed trains is predicted using sound source superposition.A step-by-step calculation of each local aerodynamic noise source is used to obtain the superimposed value of the far-field *** is consistent with the far-field noise of the whole train model’s aerodynamic *** averaged sound pressure level of the far-field longitudinal noise measurement points differs by 1.92 *** step-by-step numerical prediction method of aerodynamic noise of high-speed trains can provide a reference for the numerical prediction of aerodynamic noise generated by long marshalling high-speed trains.

关键词： High-speed train Aerodynamic noise Sound source superposition numerical prediction

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numerical prediction of machining-induced surface residual stress for TC4 cryogenic turning

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2021年第1-2期114卷 131-144页

作者： Liu, Haibo Wang, Chengxin Liu, Zhaohuan Liu, Kuo Jiang, Shaowei Wang, Yongqing Dalian Univ Technol Minist Educ Key Lab Precis & Nontradit Machining Technol Dalian 116024 Peoples R China Hebei HanGuang Ind Co Ltd Handan 056017 Peoples R China

Liquid nitrogen(LN2) cryogenic machining is a green, sustainable, and high-performance machining technology. LN2 cryogenic machining of TC4 can significantly strengthen the local cooling environment of cutting, accelerate the heat dissipation, thus effectively reduce the cutting temperature, and suppress the generation of thermal stress, reduce the residual tensile stress on the workpiece surface. In this paper, a finite element model(FEM) of numerical prediction is established to analyze the effect of LN2 cryogenic machining on residual stress distribution. Firstly, mechanism analysis of surface residual stress is carried out to explore the source of residual stress during TC4 cryogenic turning. Next, to observe residual stress distribution clearly, the cutting zone separation model is designed, and then, the material model is built to reflect the change of material properties. Then, a FEM of the numerical prediction made up of explicit dynamic solution module and standard static solution module is established to simulate residual stress distribution;after that, residual stress can be ultimately acquired by linear superposing the above two module simulation results. Based on FEM proposed in this paper, the effect of LN2 cryogenic machining on surface residual stress distribution of TC4 is analyzed, and it is indicated that LN2 cryogenic machining can reduce the residual tensile stress effectively. Finally, the experiment is carried out, and the results show that the general trend of the prediction model is the same as that of the experimental results, which greatly verify the availability of the prediction model. Research provides some reference for the numerical prediction and suppression of residual stress in the future.

关键词： TC4 Residual stress numerical prediction Finite element model(FEM) Cryogenic machining liquid nitrogen(LN2)

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Experiment and numerical prediction on Shock Sensitivity of HMX-Based Booster Explosive with Small Scale Gap Test at Low and Elevated Temperatures

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APPLIED SCIENCES-BASEL 2024年第19期14卷 8964页

作者： Yuan, Junming Linghu, Jiangqi Han, Peijiang Tian, Xiuqi Wang, Nan Yang, Qi Yang, Jia North Univ China Sch Environm & Safety Engn Taiyuan 030051 Peoples R China

In order to analyze the effect of temperature changes on the shock initiation performance of HMX-based booster explosive, which consists of 95% HMX and 5% FPM2602 by weight, a temperature calibration test of acceptor was designed. The temperature changes in the booster at low and elevated temperatures under the constraint of steel sleeve were obtained. Based on the temperature calibration results, polymethyl methacrylate (PMMA) was selected as gap material to conduct a small scale gap test (SSGT) of HMX-based booster under different temperature conditions. The corresponding critical gap thickness was tested. Based on SSGT results at different temperatures, the shock initiation processes were simulated by adjusting parameters of ignition and growth reactive rate model. The critical gap thickness and critical initiation pressure of HMX-based booster at different temperatures were numerically predicted. By combining SSGT experimental data and simulation results, the attenuation law and fitting prediction formula of the critical initiation pressure of HMX-based booster were proposed. The mechanism of temperature effect on the shock sensitivity of HMX-based booster explosive was analyzed. The research results indicate that the critical gap thickness of HMX-based booster gradually increases with the rise in temperature, and the critical initiation pressure gradually decreases during the shock initiation process under the heating temperature conditions. In addition, the simulation results show that the heated HMX-based booster under steel constraints becomes more sensitive at high temperatures (>120 degrees C), while the cooled booster is more insensitive, but its critical initial pressure does not change significantly between 88 degrees C and 120 degrees C. The experimental and numerical prediction results are important for the shock initiation safety and design of an insensitive booster explosive.

关键词： small-scale gap test booster shock sensitivity numerical prediction simulation safety

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Uncertainty analysis of linear vertical bending moment in model tests and numerical prediction

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2022年 178卷 1页

作者： Si, Hailong Yang, Peng Gu, Xuekang Hu, Jiajun Tian, Chao Feng, Qiandong Ni, Yang Huazhong Univ Sci & Technol Sch Naval Architecture & Ocean Engn Wuhan 430074 Peoples R China China Ship Sci Res Ctr 222 East Shanshui Rd Wuxi 214082 Peoples R China

Due to the complexity of model tests of wave loads, some random factors affect the accuracy of measurement results, such as model processing, coefficient calibration, counterweight, and wave creation quality. Based on the uncertainty expansion theory, a set of wave load measurement accuracy and uncertainty analysis methods for ship model in wave basin were established. The significant factors affecting accuracies of wave load tests were assessed by the linear multi-segment model tests of wave loads. Two numerical methods were used to evaluated the predic-tion errors and uncertainties of the linear vertical moment, horizontal moment and torsional moment. The research shows that with the updating of test instruments and approaches, the standard uncertainty of model test decreased. The uncertainty caused by the calibration coeffi-cient was the largest, followed by the moments of inertia of ship models. As the wave direction changes from head seas to oblique seas, the errors and uncertainties of numerical predictions begin to increase. The numerical predicting errors of vertical bending moments was the smallest, followed by horizontal bending moment and torsion error was the largest.

关键词： Uncertainty Vertical bending Springing Model test numerical prediction

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