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The analysis of drill string dynamics for extra-deep wells based on successive over-relaxation node iteration method
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作者 Wen-Chang Wang He-Yuan Yang +4 位作者 Da-Kun Luo Ming-Ming You Xing Zhou Feng Chen Qin-Feng Di 《Petroleum Science》 2025年第8期3293-3303,共11页
The complex vibration directly affects the dynamic safety of drill string in ultra-deep wells and extra-deep wells.It is important to understand the dynamic characteristics of drill string to ensure the safety of dril... The complex vibration directly affects the dynamic safety of drill string in ultra-deep wells and extra-deep wells.It is important to understand the dynamic characteristics of drill string to ensure the safety of drill string.Due to the super slenderness ratio of drill string,strong nonlinearity implied in dynamic analysis and the complex load environment,dynamic simulation of drill string faces great challenges.At present,many simulation methods have been developed to analyze drill string dynamics,and node iteration method is one of them.The node iteration method has a unique advantage in dealing with the contact characteristics between drill string and borehole wall,but its drawback is that the calculation consumes a considerable amount of time.This paper presents a dynamic simulation method of drilling string in extra-deep well based on successive over-relaxation node iterative method(SOR node iteration method).Through theoretical analysis and numerical examples,the correctness and validity of this method were verified,and the dynamics characteristics of drill string in extra-deep wells were calculated and analyzed.The results demonstrate that,in contrast to the conventional node iteration method,the SOR node iteration method can increase the computational efficiency by 48.2%while achieving comparable results.And the whirl trajectory of the extra-deep well drill string is extremely complicated,the maximum rotational speed downhole is approximately twice the rotational speed on the ground.The dynamic torque increases rapidly at the position of the bottom stabilizer,and the lateral vibration in the middle and lower parts of drill string is relatively intense. 展开更多
关键词 Extra-deep well Drill string dynamics Calculation speed-up method SOR iteration method
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An eigen-based theory for developing numerical methods for structural dynamics
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作者 Huang Chiu-Li Chang Shuenn-Yih Chang Karen 《Earthquake Engineering and Engineering Vibration》 2025年第2期333-356,共24页
The feasibility of using a problem-dependent method to solve systems of second order ODEs is corroborated by an eigen-based theory and a methodology to develop such a numerical method is constructed.The key steps of t... The feasibility of using a problem-dependent method to solve systems of second order ODEs is corroborated by an eigen-based theory and a methodology to develop such a numerical method is constructed.The key steps of this methodology are to decouple a system of ODEs of second order into a set of uncoupled ODEs of second order;next,an eigen-dependent method is proposed to approximate the solution of each uncoupled ODE of second order.It is vital to transform all eigen-dependent methods to a problem-dependent method to bypass an Eigen analysis.The development of an eigen-dependent method plays a key role in this methodology so that slow eigenmodes can be accurately integrated while there is no instability or excessive amplitude growth in fast eigenmodes.This can explain why a problem-dependent method can simultaneously combine the explicitness of each step and A-stability.Consequently,huge computational efforts can be saved for solving nonlinear stiff problems.A new family of problem-dependent methods is developed in this work so that the feasibility of the proposed methodology can be affirmed.It has almost the same performance as that of the HHT-αmethod.However,it can save more than 99.5%of CPU demand in approximating a solution for a system of 1000 nonlinear second order ODEs. 展开更多
关键词 an eigen-based theory unconditional stability accuracy eigen-dependent method structure-dependent method nonlinear dynamics
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Nonlinear dynamics of intricate constrained fluid-conveying pipelines based on the global modal method
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作者 Ye TANG Yuxiang WANG +2 位作者 Hujie ZHANG Tianzhi YANG Fantai MENG 《Applied Mathematics and Mechanics(English Edition)》 2025年第10期1851-1866,共16页
In recent years,scholars around the world have shown increasing interest in elastic support structures,leading to significant progress in dynamic modeling techniques for pipeline systems.Although multiple analytical a... In recent years,scholars around the world have shown increasing interest in elastic support structures,leading to significant progress in dynamic modeling techniques for pipeline systems.Although multiple analytical approaches exist,engineers increasingly prioritize computationally efficient,precise low-order models for practical implementation.In order to address this need,this study develops an innovative nonlinear dynamic formulation for pipelines accounting for both foundation and boundary nonlinearities.The proposed solution methodology initiates with global mode extraction using the global mode technique,followed by a detailed implementation procedure.Model validation is conducted through a cantilever pipeline case study featuring nonlinear support conditions,where strong agreement between the proposed model's predictions and finiteelement benchmark solutions demonstrates its reliability.Subsequently,a comprehensive parametric study investigates the combined effects of foundation stiffness,boundary constraints,excitation intensity,and nonlinear interaction terms on the vibrational response of the cantilever pipe.This systematic approach yields critical insights for practical engineering designs and applications. 展开更多
关键词 fluid-conveying pipeline complex constraint nonlinear dynamics global modal method
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CFD Simulation of Passenger Car Aerodynamics and Body Parameter Optimization
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作者 Jichao Li Xuexin Zhu +2 位作者 Cong Zhang Shiwang Dang Guang Chen 《Fluid Dynamics & Materials Processing》 2025年第9期2305-2329,共25页
The rapid advancement of technology and the increasing speed of vehicles have led to a substantial rise in energy consumption and growing concern over environmental pollution.Beyond the promotion of new energy vehicle... The rapid advancement of technology and the increasing speed of vehicles have led to a substantial rise in energy consumption and growing concern over environmental pollution.Beyond the promotion of new energy vehicles,reducing aerodynamic drag remains a critical strategy for improving energy efficiency and lowering emissions.This study investigates the influence of key geometric parameters on the aerodynamic drag of vehicles.A parametric vehicle model was developed,and computational fluid dynamics(CFD)simulations were conducted to analyse variations in the drag coefficient(C_(d))and pressure distribution across different design configurations.The results reveal that the optimal aerodynamic performance—characterized by a minimized drag coefficient—is achieved with the following parameter settings:engine hood angle(α)of 15°,windshield angle(β)of 25°,rear window angle(γ)of 40°,rear upwards tail lift angle(θ)of 10°,ground clearance(d)of 100 mm,and side edge angle(s)of 5°.These findings offer valuable guidance for the aerodynamic optimization of vehicle body design and contribute to strategies aimed at energy conservation and emission reduction in the automotive sector. 展开更多
关键词 Automotive aerodynamic characteristics flow field aerodynamic drag drag reduction optimization cfd(computational fluid dynamics)
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基于CFD数值仿真的延迟型高度阀稳态性能 被引量:1
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作者 艾佳 蔡一庆 +3 位作者 王瓅楠 范学京 李罡 付翔 《船舶工程》 北大核心 2025年第5期48-54,共7页
[目的]船舶空气弹簧隔振系统需保证设备与管路等附属结构的相对位移在一定范围,以避免受到外界冲击时出现系统级的损伤。目前主要采用机械式限位装置实现极限位置控制,灵活性差。高度调节阀通过感知对象相对位移变化,主动对空气弹簧充... [目的]船舶空气弹簧隔振系统需保证设备与管路等附属结构的相对位移在一定范围,以避免受到外界冲击时出现系统级的损伤。目前主要采用机械式限位装置实现极限位置控制,灵活性差。高度调节阀通过感知对象相对位移变化,主动对空气弹簧充放气实现负载位置的稳定调节,由于灵活性强、可靠性高,在轨道车辆中已广泛应用。[方法]利用计算流体动力学(CFD)技术建立延迟型高度阀高精度仿真模型,探究不同参数下阀门的稳态流量响应特征;通过正交试验方法,建立阀门设计参数与性能之间的映射关系。[结果]结果表明:阀门流量随前后压差呈线性增长,而随环境温度呈单调下降趋势;在阀门开度为0~5%,输出流量急剧增加,后趋于稳定。进一步分析发现,阀门前后压差对输出流量的影响最大,环境温度影响次之,阀门开度影响最小。[结论]研究结果为延迟型高度阀在船舶空气弹簧隔振系统的拓展应用提供了自主化和正向设计依据。 展开更多
关键词 延迟型高度阀 计算流体力学 数值仿真 稳态性能 正交试验
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基于CFD的5×5单跨燃料组件热工水力可靠性设计优化
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作者 张哲 吴天淏 +2 位作者 姜潮 金德升 王俊涛 《核动力工程》 北大核心 2025年第5期124-131,共8页
为探究燃料组件运行工况下热工水力不确定性参数对其安全性与经济性的影响,采用计算流体动力学(CFD)方法对5×5单跨燃料组件进行仿真模拟,并发展基于样本的迁移学习方法开展可靠性分析,从而高效地实现燃料组件可靠性设计优化。结果... 为探究燃料组件运行工况下热工水力不确定性参数对其安全性与经济性的影响,采用计算流体动力学(CFD)方法对5×5单跨燃料组件进行仿真模拟,并发展基于样本的迁移学习方法开展可靠性分析,从而高效地实现燃料组件可靠性设计优化。结果表明,在燃料棒总表面热流密度一定的情况下,通过优化入口流速以及热流密度的分布,燃料棒外表面最高温度降低了2.6℃,且在99%的概率下确保冷却剂温升大于2℃,压降小于4400 Pa。优化结果在保证经济效益的前提下提高了热工安全性,为燃料组件的优化设计提供了新的研究方法。 展开更多
关键词 核燃料组件 计算流体动力学(cfd) 可靠性设计优化
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基于EFD和CFD组合方法的肥大船型功率预报研究 被引量:2
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作者 高旋 高玉玲 陈伟民 《中国航海》 北大核心 2025年第1期150-156,共7页
对三种肥大船型不同载况下形状因子(1+k)的确定方法及其适应性开展研究,探讨建立基于模型试验流体动力学(EFD)和计算流体动力学(CFD)组合方法的肥大船型实船功率预报方法。以某肥大型散货船为主要研究对象,分别采用模型试验和数值模拟... 对三种肥大船型不同载况下形状因子(1+k)的确定方法及其适应性开展研究,探讨建立基于模型试验流体动力学(EFD)和计算流体动力学(CFD)组合方法的肥大船型实船功率预报方法。以某肥大型散货船为主要研究对象,分别采用模型试验和数值模拟方法确定形状因子并进行对比分析,然后采用EFD和CFD组合方法进行实船性能预报。研究表明:基于CFD获取形状因子并结合模型试验进行肥大船型功率预报,结果与实船试航结果比较接近且在误差允许范围内,验证基于EFD和CFD组合方法预报实船航速功率具有实用性和可行性。 展开更多
关键词 模型试验流体动力学 计算流体动力学 模型试验与数值计算组合方法 形状因子 实船功率预报
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基于CFD-DPM模型的不同生态抛枕防护效果分析
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作者 孙洪广 洪良贞 +1 位作者 王茂枚 王连 《长江科学院院报》 北大核心 2025年第4期19-26,44,共9页
天然河道中弯曲边坡是受侵蚀的严重区域,弯曲边坡防护是河道治理的重大难题。基于生态护坡理念,对比研究了砂石填装的不同形状抛枕在弯道侵蚀中的防护效果。根据实际河道结构,构建了弯道河床几何模型,进而利用计算流体力学-离散相模型(C... 天然河道中弯曲边坡是受侵蚀的严重区域,弯曲边坡防护是河道治理的重大难题。基于生态护坡理念,对比研究了砂石填装的不同形状抛枕在弯道侵蚀中的防护效果。根据实际河道结构,构建了弯道河床几何模型,进而利用计算流体力学-离散相模型(CFD-DPM)方法分析在弯曲河道凹岸侧投放长方体、半球体和半圆柱体抛枕的护岸效果。分析结果表明:在水流速度v=0.5 m/s的条件下,放置有抛枕的3种模型中,长方体抛枕附近的凹岸受到的压力最小,半圆柱体抛枕中颗粒雷诺数最小;半圆柱体抛枕阻挡的颗粒量最多、颗粒的平均速度最小,比无抛枕模型中的颗粒平均速度小9%;放置长方体抛枕的护岸模式下,对抛枕附近的凹岸有较好的防护效果,放置半圆柱体抛枕的护岸模式下,阻沙效果最佳。 展开更多
关键词 弯曲边坡防护 生态护坡 砂石抛枕 弯道河床几何模型 cfd-DPM方法 防护效果
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An efficient uncertainty propagation method for nonlinear dynamics with distribution-free P-box processes 被引量:1
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作者 Licong ZHANG Chunna LI +3 位作者 Hua SU Yuannan XU Andrea Da RONCH Chunlin GONG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第12期116-138,共23页
The distribution-free P-box process serves as an effective quantification model for timevarying uncertainties in dynamical systems when only imprecise probabilistic information is available.However,its application to ... The distribution-free P-box process serves as an effective quantification model for timevarying uncertainties in dynamical systems when only imprecise probabilistic information is available.However,its application to nonlinear systems remains limited due to excessive computation.This work develops an efficient method for propagating distribution-free P-box processes in nonlinear dynamics.First,using the Covariance Analysis Describing Equation Technique(CADET),the dynamic problems with P-box processes are transformed into interval Ordinary Differential Equations(ODEs).These equations provide the Mean-and-Covariance(MAC)bounds of the system responses in relation to the MAC bounds of P-box-process excitations.They also separate the previously coupled P-box analysis and nonlinear-dynamic simulations into two sequential steps,including the MAC bound analysis of excitations and the MAC bounds calculation of responses by solving the interval ODEs.Afterward,a Gaussian assumption of the CADET is extended to the P-box form,i.e.,the responses are approximate parametric Gaussian P-box processes.As a result,the probability bounds of the responses are approximated by using the solutions of the interval ODEs.Moreover,the Chebyshev method is introduced and modified to efficiently solve the interval ODEs.The proposed method is validated based on test cases,including a duffing oscillator,a vehicle ride,and an engineering black-box problem of launch vehicle trajectory.Compared to the reference solutions based on the Monte Carlo method,with relative errors of less than 3%,the proposed method requires less than 0.2% calculation time.The proposed method also possesses the ability to handle complex black-box problems. 展开更多
关键词 Nonlinear dynamics Uncertainty propagation Imprecise probability Distribution-free P-box processes Chebyshev method
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水悬浮造粒搅拌釜内气液固三相混合特性CFD模拟 被引量:1
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作者 卢玉成 黄涛 +4 位作者 罗亚军 刘佳辉 巩飞艳 严超宇 刘晓星 《化工进展》 北大核心 2025年第8期4556-4566,共11页
针对含能材料水悬浮造粒工艺气液固三相搅拌过程,采用Eulerian多相流流体体积(VOF)模型对搅拌釜内气液相界面变化及固相分散行为进行了数值模拟,考察了转速和液相黏度对自由液面形态、固相浓度分布及固相速度分布变化的影响。结果表明,... 针对含能材料水悬浮造粒工艺气液固三相搅拌过程,采用Eulerian多相流流体体积(VOF)模型对搅拌釜内气液相界面变化及固相分散行为进行了数值模拟,考察了转速和液相黏度对自由液面形态、固相浓度分布及固相速度分布变化的影响。结果表明,该模型能够合理预测具有自由液面的气液固三相搅拌过程;在250~350r/min转速内,提升转速有助于减少自由液面及边壁区域的固相富集,促进固相的均匀分散;当转速超过350r/min时,空气卷吸效应增强,大量气泡进入悬浮液。在0.001~0.1Pa·s液相黏度范围内,提高黏度可增强湍流剪切作用,抑制固相沉降,有利于固相的均匀悬浮;当液相黏度由0.1Pa·s增至0.5Pa·s时,固相流动性降低,不利于搅拌过程的稳定运行。本文为水悬浮造粒工艺的操作和优化提供了理论参考。 展开更多
关键词 含能材料 水悬浮 搅拌釜 计算流体力学 多相流
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A stable implicit nodal integration-based particle finite element method(N-PFEM)for modelling saturated soil dynamics 被引量:1
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作者 Liang Wang Xue Zhang +1 位作者 Jingjing Meng Qinghua Lei 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期2172-2183,共12页
In this study,we present a novel nodal integration-based particle finite element method(N-PFEM)designed for the dynamic analysis of saturated soils.Our approach incorporates the nodal integration technique into a gene... In this study,we present a novel nodal integration-based particle finite element method(N-PFEM)designed for the dynamic analysis of saturated soils.Our approach incorporates the nodal integration technique into a generalised Hellinger-Reissner(HR)variational principle,creating an implicit PFEM formulation.To mitigate the volumetric locking issue in low-order elements,we employ a node-based strain smoothing technique.By discretising field variables at the centre of smoothing cells,we achieve nodal integration over cells,eliminating the need for sophisticated mapping operations after re-meshing in the PFEM.We express the discretised governing equations as a min-max optimisation problem,which is further reformulated as a standard second-order cone programming(SOCP)problem.Stresses,pore water pressure,and displacements are simultaneously determined using the advanced primal-dual interior point method.Consequently,our numerical model offers improved accuracy for stresses and pore water pressure compared to the displacement-based PFEM formulation.Numerical experiments demonstrate that the N-PFEM efficiently captures both transient and long-term hydro-mechanical behaviour of saturated soils with high accuracy,obviating the need for stabilisation or regularisation techniques commonly employed in other nodal integration-based PFEM approaches.This work holds significant implications for the development of robust and accurate numerical tools for studying saturated soil dynamics. 展开更多
关键词 Particle finite element method Nodal integration Dynamic saturated media Second-order cone programming(SOCP)
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基于CFD−DPM的空气幕协同排风罩增效除尘研究
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作者 丁厚成 许婉萍 +2 位作者 邓权龙 陈圳杨 朱强 《安徽工业大学学报(自然科学版)》 2025年第1期62-71,共10页
以某机械厂打磨车间为研究对象,利用Solidworks软件建立带有空气幕协同排风罩除尘的打磨车间模型,基于气固两相流理论,采用计算流体力学离散颗粒模型(CFD−DPM)模拟分析空气幕送风速度、射流角度和射流宽度对除尘效率的影响,选取空气幕... 以某机械厂打磨车间为研究对象,利用Solidworks软件建立带有空气幕协同排风罩除尘的打磨车间模型,基于气固两相流理论,采用计算流体力学离散颗粒模型(CFD−DPM)模拟分析空气幕送风速度、射流角度和射流宽度对除尘效率的影响,选取空气幕的最优参数;在此基础上,对比分析未开启排风罩、开启排风罩、同时开启排风罩与空气幕3种工况的风速分布、粉尘运移轨迹及粉尘质量浓度分布,探讨空气幕协同排风罩除尘的效果。结果表明:粉尘最大浓度、呼吸带粉尘浓度随空气幕送风速度、射流宽度的增大而减小,但不随空气幕射流角度的变化而变化;粉尘浓度随地面高度的增大先增后减,不同高度处粉尘浓度变化趋势基本一致;当空气幕射流宽度30 mm、射流角度30°、送风速度3 m/s时,通风除尘效果最佳,除尘效率高达94.2%。相比于仅开启排风罩,排风罩与空气幕协同作用下的除尘效率提高了38.8%,空气幕协同排风罩对车间除尘具有较好的增效作用。 展开更多
关键词 打磨车间 金属粉尘 排风罩 空气幕 计算流体力学(cfd) 离散颗粒模型(DPM) 除尘 职业健康
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基于CFD-DPM的微气旋结构中粉尘捕集特性模拟研究 被引量:1
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作者 张虎 郭恒 +3 位作者 何新建 常彬彬 耿凡 陈曦 《中国安全生产科学技术》 北大核心 2025年第3期113-118,共6页
为探究煤矿工人个体防护多元方法,基于煤矿井下粉尘污染背景,采用气旋分离技术用于个体初级除尘,研究微气旋结构的粉尘捕集特性:建立并改进微型气旋结构,采用CFD-DPM方法、结合RNG k-ε对微型旋风分离结构中的多相流动过程进行模拟研究... 为探究煤矿工人个体防护多元方法,基于煤矿井下粉尘污染背景,采用气旋分离技术用于个体初级除尘,研究微气旋结构的粉尘捕集特性:建立并改进微型气旋结构,采用CFD-DPM方法、结合RNG k-ε对微型旋风分离结构中的多相流动过程进行模拟研究,着重分析粉尘颗粒的分离特性,探讨影响气旋结构中粉尘分离效率的主要因素。研究结果表明:气旋结构的圆锥体内流场湍流剧烈,发生涡旋核心偏移的摆尾现象;适当增加入口风速有利于提升粉尘颗粒在微气旋结构中的捕集率,大粒径粉尘的捕集率较高,排气管直径的增加会加快气旋装置内外部旋流的速度,可提高粉尘的捕集率。研究结果可为改进微型气旋结构、丰富个体防护方法提供参考。 展开更多
关键词 微气旋结构 粉尘 分离特性 影响因素 cfd-DPM方法
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基于WRF模式的CFD与LSTM技术对低空风切变数值模拟研究 被引量:2
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作者 董泽新 吴硕岩 +5 位作者 叶芳 陈丽晶 李毅 孙辰博 徐峰 刘磊 《高原气象》 北大核心 2025年第2期546-562,共17页
为提升低空风切变预报精度,本文综合运用欧洲中期天气预报中心第五代再分析资料[European Centre for Medium-Range Weather Forecasts(ECMWF)fifth-generation reanalysis data,ERA5]和美国国家环境预报中心(National Centers for Envi... 为提升低空风切变预报精度,本文综合运用欧洲中期天气预报中心第五代再分析资料[European Centre for Medium-Range Weather Forecasts(ECMWF)fifth-generation reanalysis data,ERA5]和美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)的FNL全球再分析资料(Final Operational Global Analysis)、先进星载热发射和反射辐射仪全球数字高程模型以及兰州中川机场的实况观测资料,采用中尺度数值天气预报模式(Weather Research and Forecasting Model,WRF)、WRF结合计算流体动力学(Computational Fluid Dynamics,CFD)方法、长短期神经网络(Long Short-Term Memory,LSTM)方法,对2021年4月15-16日兰州中川机场的两次风切变过程进行模拟分析。结果表明:(1)在小于1 km的网格中使用大涡模拟,WRF模式在单个站点风速模拟任务中表现更好,但在近地面水平风场风速模拟效果上,不如WRF模式结合计算流体力学模型方案;(2)对于飞机降落过程中遭遇的两次低空风切变的模拟,WRF-LES和WRF-CFD两种模式都可以模拟出第一次低空风切变,而第二次受传入模式的WRF风速数据值较小的影响,两种模式风速差都没有达到阈值,需要在后续工作中进一步验证;(3)低风速条件(6 m·s^(-1))下,基于LSTM的单变量风速预测模型平均绝对误差基本维持在0.59 m·s^(-1),能较好地把握不同地形与环流背景条件下风速变化的非线性关系,虽然受到WRF误差和观测要素不全的限制,多变量风速预测能在保证平均绝对百分比误差小于6.60%的情况下,以更高的计算效率和泛化能力实现风速预测。本文不仅验证了WRF-CFD和WRF-LES耦合方案在风场和低空风切变预报中的差异,还探讨了基于LSTM的风速预测的可行性和准确性,期望为提高风场模拟精度,缩短精细风场模拟时间提供新的视角和方法。 展开更多
关键词 低空风切变 计算流体力学模型(cfd) WRF模式 大涡模拟 长短期记忆网络
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基于CFD-DEM耦合的土壤传热过程模拟
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作者 江洁 赵庆富 《安徽农业科学》 2025年第10期210-216,共7页
为探明射流燃烧火焰在除草时的温度分布,分析射流火焰在土壤颗粒及多孔介质中的传热特性,通过测量和标定土壤颗粒参数,建立火焰喷头、土壤颗粒床以及土壤多孔介质模型。采用计算流体力学(CFD)与离散元法(DEM)耦合方法对喷头射流燃烧火... 为探明射流燃烧火焰在除草时的温度分布,分析射流火焰在土壤颗粒及多孔介质中的传热特性,通过测量和标定土壤颗粒参数,建立火焰喷头、土壤颗粒床以及土壤多孔介质模型。采用计算流体力学(CFD)与离散元法(DEM)耦合方法对喷头射流燃烧火焰温度在土层中的热特性传递进行数值模拟试验。结果表明,当喷头高度为100 mm时最高温度可达958 K,温度影响范围近似为半径90 mm的圆,传热深度可达17 mm。当喷头高度为200 mm时最高温度为848 K,影响范围近似为半径40 mm的圆,温度影响范围和影响半径都与喷头高度呈线性关系,均随着喷头高度的增加而减小。通过试验测得火焰喷头在距离地面高度分别为100、125、150、175、200 mm时土壤最高温度分别为926.15、913.95、887.35、860.85、818.35 K。 展开更多
关键词 传热特性 计算流体力学 离散元法 燃烧 土壤
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Comparative study of nudged elastic band and molecular dynamics methods for diffusion kinetics in solid-state electrolytes
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作者 林啊鸣 石晶 +1 位作者 魏苏淮 孙宜阳 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期96-100,共5页
Considerable efforts are being made to transition current lithium-ion and sodium-ion batteries towards the use of solid-state electrolytes.Computational methods,specifically nudged elastic band(NEB)and molecular dynam... Considerable efforts are being made to transition current lithium-ion and sodium-ion batteries towards the use of solid-state electrolytes.Computational methods,specifically nudged elastic band(NEB)and molecular dynamics(MD)methods,provide powerful tools for the design of solid-state electrolytes.The MD method is usually the choice for studying the materials involving complex multiple diffusion paths or having disordered structures.However,it relies on simulations at temperatures much higher than working temperature.This paper studies the reliability of the MD method using the system of Na diffusion in MgO as a benchmark.We carefully study the convergence behavior of the MD method and demonstrate that total effective simulation time of 12 ns can converge the calculated diffusion barrier to about 0.01 eV.The calculated diffusion barrier is 0.31 eV from both methods.The diffusion coefficients at room temperature are 4.3×10^(-9) cm^(2)⋅s^(−1) and 2.2×10^(-9) cm^(2)⋅s^(−1),respectively,from the NEB and MD methods.Our results justify the reliability of the MD method,even though high temperature simulations have to be employed to overcome the limitation on simulation time. 展开更多
关键词 nudged elastic band method molecular dynamics solid electrolyte ion transport density func-tional theory
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基于CFD模拟的人工神经网络动态溯源模型
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作者 史天乐 李飞 +2 位作者 陈昇 卢春喜 王维 《化工进展》 北大核心 2025年第8期4772-4784,共13页
危险气体泄漏事故早期处理不当,可能会引发二次燃爆等次生灾害,因此开发一种快速泄漏源定位的气体溯源方法至关重要。气体溯源是气体扩散的逆问题,在科学研究和工程应用中仍具有挑战性,人工神经网络与溯源定位方案的结合为解决这一反问... 危险气体泄漏事故早期处理不当,可能会引发二次燃爆等次生灾害,因此开发一种快速泄漏源定位的气体溯源方法至关重要。气体溯源是气体扩散的逆问题,在科学研究和工程应用中仍具有挑战性,人工神经网络与溯源定位方案的结合为解决这一反问题提供了一种可行途径,有望实现快速准确的溯源定位。本文基于计算流体动力学模拟结果建立动态气体溯源数据集,搭建了基于传感器数据序列实时预测泄漏源位置的长短期记忆神经网络动态溯源模型,并对模型进行训练和优化。结果表明:基于人工神经网络的动态溯源模型成功实现了对泄漏源的准确预测,预测点与真实泄漏源位置的距离在20m以内,模型的准确率达97.49%。在输入一组序列浓度数据后,可以在0.04737s内预测泄漏源的初步位置,显著快于传统的溯源定位方法。 展开更多
关键词 计算流体力学 模拟 神经网络 动态溯源定位模型 反问题
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A flexible multiscale algorithm based on an improved smoothed particle hydrodynamics method for complex viscoelastic flows
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作者 Jinlian REN Peirong LU +2 位作者 Tao JIANG Jianfeng LIU Weigang LU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第8期1387-1402,共16页
Viscoelastic flows play an important role in numerous engineering fields,and the multiscale algorithms for simulating viscoelastic flows have received significant attention in order to deepen our understanding of the ... Viscoelastic flows play an important role in numerous engineering fields,and the multiscale algorithms for simulating viscoelastic flows have received significant attention in order to deepen our understanding of the nonlinear dynamic behaviors of viscoelastic fluids.However,traditional grid-based multiscale methods are confined to simple viscoelastic flows with short relaxation time,and there is a lack of uniform multiscale scheme available for coupling different solvers in the simulations of viscoelastic fluids.In this paper,a universal multiscale method coupling an improved smoothed particle hydrodynamics(SPH)and multiscale universal interface(MUI)library is presented for viscoelastic flows.The proposed multiscale method builds on an improved SPH method and leverages the MUI library to facilitate the exchange of information among different solvers in the overlapping domain.We test the capability and flexibility of the presented multiscale method to deal with complex viscoelastic flows by solving different multiscale problems of viscoelastic flows.In the first example,the simulation of a viscoelastic Poiseuille flow is carried out by two coupled improved SPH methods with different spatial resolutions.The effects of exchanging different physical quantities on the numerical results in both the upper and lower domains are also investigated as well as the absolute errors in the overlapping domain.In the second example,the complex Wannier flow with different Weissenberg numbers is further simulated by two improved SPH methods and coupling the improved SPH method and the dissipative particle dynamics(DPD)method.The numerical results show that the physical quantities for viscoelastic flows obtained by the presented multiscale method are in consistence with those obtained by a single solver in the overlapping domain.Moreover,transferring different physical quantities has an important effect on the numerical results. 展开更多
关键词 multiscale method improved smoothed particle hydrodynamics(SPH) dissipative particle dynamics(DPD) multiscale universal interface(MUI) complex viscoelastic flow
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基于神经网络与CFD相结合的仿蜻蜓串联扑翼气动性能优化研究
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作者 钱广 朱建阳 +3 位作者 蔡芸 汪超 徐启炎 侯宇 《航空动力学报》 北大核心 2025年第3期195-206,共12页
为了提升仿蜻蜓串联扑翼的气动性能,采用神经网络与CFD相结合的方法,系统分析了扭转角幅值,翼间距和前后翼相位差变化对仿蜻蜓串联扑翼升举效率的影响。研究结果表明:扭转角幅值,翼间距和前后翼相位差变化对仿蜻蜓串联扑翼的气动性能具... 为了提升仿蜻蜓串联扑翼的气动性能,采用神经网络与CFD相结合的方法,系统分析了扭转角幅值,翼间距和前后翼相位差变化对仿蜻蜓串联扑翼升举效率的影响。研究结果表明:扭转角幅值,翼间距和前后翼相位差变化对仿蜻蜓串联扑翼的气动性能具有重要影响。就所研究的参数范围,通过神经网络优化后,最优和最差参数组合扑翼的升举效率相差90.33%。进一步通过对不同参数组合仿蜻蜓串联扑翼的流场分析,发现优化参数组合的串联扑翼前翼脱落的尾涡可以重新附着在后翼表面,减弱后翼上冲程时的涡旋强度,降低扑翼的能量消耗,从而使扑翼获得更好的气动性能。 展开更多
关键词 串联扑翼 神经网络 升举效率 cfd数值模拟 田口方法
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基于CFD-FEM耦合方法的冰柱碰撞响应研究
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作者 宋英龙 杨博睿 +3 位作者 赵禹 杨碧野 郑瑜娜 张桂勇 《振动与冲击》 北大核心 2025年第15期67-74,共8页
碰撞冰载荷是影响极地海洋结构物作业安全的重要因素。基于CFD(computational fluid dynamics)软件STAR-CCM+和FEM软件Abaqus协同仿真,构建了计算结构物-浮冰-水相互作用的数值模型,开展了圆柱形结构物与方形浮冰的碰撞响应研究并分析... 碰撞冰载荷是影响极地海洋结构物作业安全的重要因素。基于CFD(computational fluid dynamics)软件STAR-CCM+和FEM软件Abaqus协同仿真,构建了计算结构物-浮冰-水相互作用的数值模型,开展了圆柱形结构物与方形浮冰的碰撞响应研究并分析了不同因素对碰撞响应的影响。进一步从能量转换的角度,提出了一种考虑浮冰初始旋转的碰撞力修正模型。分析了碰撞前、碰撞中和碰撞后阶段对碰撞力峰值的影响,实现了对带有初始旋转的浮冰碰撞载荷的快速估算。研究发现,碰撞前浮冰速度衰减、碰撞持续时间和碰撞后浮冰的转动对碰撞力均有较大影响,碰撞力随浮冰旋转角度增大呈现出先增大后减小的变化趋势。 展开更多
关键词 cfd-FEM耦合 协同仿真 浮冰 结构物 碰撞响应
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