COMSOL Multiphysics在锂离子电池中的应用

作为一种具有前景的能量存储系统,锂离子电池需要进一步提高能量密度、功率密度、可靠性和循环稳定性,以满足不断增长的大型能源存储、电动汽车和便携式电子设备需求。当前对锂离子电池的实验研究仍然面临多个挑战,这些挑战包括电解液的导电性和安全性、高能量负极的沉积-剥离机制的优化、高能量正极的循环电压和容量维持、高电流条件下的界面极化和容量释放,以及在极端电流-温度-针刺条件下的热失控管理等问题。这些问题涉及到电-化-力-热等多个场的耦合作用,需要进行协同优化处理。COMSOL Multiphysics提供了一种可行的工具,通过求解多物理场耦合的连续方程,能够同时考虑载流子浓度、电流密度、电-化学势、温度、应力/应变和几何形态等综合信息的演化。本文概述了该工具在锂离子电池的电解液、负极和正极设计等方面的研究,并聚焦于多场耦合对电池性能的综合影响、多场耦合模拟方法以及理论模拟与实验表征的结合。最后,本文对理论与实验联合研究中的多场和多尺度问题进行了展望。

Toward a fundamental understanding of the heterogeneous multiphysics behaviors of silicon monoxide/graphite composite anodes

Silicon monoxide(SiO)(silicon[Si]mixed with silicon dioxide[SiO_(2)])/graphite(Gr)composite material is one of the most commercially promising anode materials for the next generation of high-energy-density lithium-ion batteries.The major bottleneck for SiO/Gr composite anode is the poor cyclability arising from the stress/strain behaviors due to the mismatch between two heterogenous materials during the lithiation/delithiation process.To date,a meticulous and quantitative understanding of the highly nonlinear coupling behaviors of such materials is still lacking.Herein,an electro–chemo–mechanics-coupled detailed model containing particle geometries is established.The underlying mechanism of the regulation between SiO and Gr components during electrochemical cycling is quantitatively revealed.We discover that increasing the SiO weight percentage(wt%)reduces the utilization efficiency of the active materials at the same 1C rate charging and enhances the hindering effects of stress-driven flux on diffusion.In addition,the mechanical constraint demonstrates a balanced effect on the overall performance of cells and the local behaviors of particles.This study provides new insights into the fundamental interactions between SiO and Gr materials and advances the investigation methodology for the design and evaluation of next-generation high-energydensity batteries.

Experimental investigation of omnidirectional multiphysics bilayer invisibility cloak with anisotropic geometry

Thermal-electric bilayer invisibility cloak can prevent the heat flux and electric current from touching the object without distorting the external temperature and electric potential fields simultaneously.In this paper,we design an omnidirectional thermal-electric invisibility cloak with anisotropic geometry.Based on the theory of neutral inclusion,the anisotropic effective thermal and electric conductivities of confocal elliptical bilayer core-shell structure are derived,thus obtaining the anisotropic matrix material to eliminate the external disturbances omnidirectionally.The inner shell of the cloak is selected as an insulating material to shield the heat flux and electric current.Then,the omnidirectional thermal-electric cloaking effect is verified numerically and experimentally based on the theoretical anisotropic matrix and manufactured composite structure,respectively.Furthermore,we achieve the thermal-electric cloaking effect under a specific direction of heat flux and electric current using the isotropic natural materials to broaden the selection range of materials.The method proposed to eliminate anisotropy and achieve the omnidirectional effect could also be expanded to other different physical fields for the metadevices with different functions.

A 2D stability analysis of the rock surrounding underground liquified natural gas storage cavern based on COMSOL Multiphysics

Underground liquified natural gas(LNG)storage is essential in guaranteeing national energy strategic reserves,and its construction is being accelerated.The stability of surrounding rock of underground LNG storage caverns under stress-low temperature coupling effect is the key factor determining the feasibility of LNG storage.First,a mathematical model used for controlling the stress-low temperature coupling and the processes of rock damage evolution is given,followed by a 2-D numerical execution process of the mathematical model mentioned above described based on Comsol Multiphysics and Matlab code.Finally,a series of 2-D simulations are performed to study the influence of LNG storage cavern layout,burial depth,temperature and internal pressure on the stability of surrounding rocks of these underground storage caverns.The results indicate that all the factors mentioned above affect the evolution of deformation and plastic zone of surrounding rocks.The research results contribute to the engineering design of underground LNG storage caverns.

基于COMSOL Multiphysics的经皮心肌内室间隔射频消融仿真模型构建及应用

目的:构建一种经皮心肌内室间隔射频消融仿真模型,探究不同激励电压、不同消融时间对消融区域的影响。方法:以梗阻性肥厚型心肌病患者的术前CT数据为基础,利用Mimics软件实现心脏各区域组织的分割与三维表面重建,通过SolidWorks软件将重建后的各部分转化为三维实体模型,并将其与在COMSOL Multiphysics仿真软件中建立的电极针结构结合在一起,得到梗阻性肥厚型心肌病的经皮心肌内室间隔射频消融仿真模型。基于该模型设置电磁、热多物理场边界条件,并对组织温度分布以及消融时间、激励电压对消融区域的影响进行仿真分析。结果:利用该模型可以实现经皮心肌内室间隔射频消融的仿真分析,且不同的激励电压、不同的消融时间对有效消融区域具有明显的影响。结论:构建的经皮心肌内室间隔射频消融仿真模型为后续开展多种因素对消融结局的影响提供了模型基础,对进一步研究实际临床治疗中的参数优化具有重要意义。

基于COMSOL Multiphysics的不同水头压力下水热耦合分析

冻土的水热耦合问题一直是冻胀融沉的主要原因之一,涉及到土壤中水分的迁移、热量的传递以及相变过程。在多年冻土和季节冻土区,由于环境因素的影响,冻土路基容易发生不均匀沉降、冻胀融沉等灾害,这些灾害都与水分迁移、相变以及温度变化息息相关。为了解决冻土水热耦合问题,本文通过COMSOL Multiphysic软件建立水热耦合的二维模型,研究不同水头压力作用下同一时间段温度和压力的影响、对流出边界总热通量的影响、对总液态水体积的影响,以及对最低温度的影响进行分析,模拟了3种不同水头压力的工况。结果表明:同一时间段的温度和压力随着水头压力的增加而变化;流出边界离开系统的总热通量也随着水头压力的增大而增大;不同工况下水头梯度越大,冰块融化速度越快,达到总液态水体积最大值的时间越短。The hydrothermal coupling problem of frozen soil has always been one of the main reasons for frost heave and thaw settlement, involving the migration of water in the soil, heat transfer, and phase change process. In permafrost and seasonal permafrost areas, due to environmental factors, permafrost roadbeds are prone to disasters such as uneven settlement, frost heave and thaw settlement, which are closely related to water migration, phase change, and temperature changes. In order to solve the problem of hydrothermal coupling in permafrost, this paper establishes a two-dimensional model of hydrothermal coupling using COMSOL Multiphysic software. The influence of temperature and pressure at the same time period under different head pressures, the influence on the total heat flux at the outflow boundary, the influence on the total liquid water volume, and the influence on the minimum temperature are studied. Three different head pressure working conditions are simulated. The results show that the temperature and pressure during the same time period change with the increase of head pressure;The total heat flux leaving the system at the outflow boundary also increases with the increase of head pressure;The larger the head gradient under different working conditions, the faster the melting rate of ice, and the shorter the time to reach the maximum total liquid water volume.

COMSOL Multiphysics在物理化学教学中的应用

将计算仿真融入大学化学专业课程的讲授是帮助学生具体化抽象概念、提升教学质量的新思路。本文介绍了多场物理仿真软件COMSOL Multiphysics的基本原理和操作,并结合大学物理化学课程的教学内容,总结说明了该软件在相平衡、化学平衡以及化学动力学等章节中的应用实例。由学生反馈可知,计算模拟软件在课堂教学中的可视化的演示,增强了学生对所学知识的理解和掌握,提高了学生的学习热情和思考深度。

基于COMSOL Multiphysics 软件的地下水污染物运移模拟研究

地下水环境质量是衡量生态文明建设水平的重要指标,应用科学有效的计算方法模拟地下水污染物渗漏的影响范围及程度,对于地下水污染的防治有着极其重要的意义。COMSOL Multiphysics作为一款多物理场建模与仿真软件,能够较好地结合现实水文地质条件,有效地模拟自然界一些水文地质过程发生和发展过程,对进行以预防和修复治理为目的的地下水污染物数值模拟预测具有十分重要的应用价值。本文根据研究区的水文地质特征,利用COMSOL Multiphysics软件构建了地下水数值模型,对研究区地下水污染物运移规律进行分析,对污染物运移轨迹进行模拟与预测。预测结果表明,氯仿、石油烃污染物在释放1 000 a时的影响范围分别是6.3×10^(6)m^(2)和5.7×10^(6)m^(2)。由于地下水流速相对较慢,污染物扩散速度极其缓慢,研究区内污染物需要在百年时间量级上才可能形成较大规模扩散,短期内对地下水环境的污染风险较小。模拟结果为研究区的地下水环境评价和防范措施提供了科学依据。

基于COMSOL Multiphysics的混合坝接头数值分析

为保证工程设计的合理性和安全性,利用COMSOL Multiphysics对混合坝接头形式和防渗系统等进行三维有限元分析,考虑施工填筑路径、重力坝与土石坝接触的力学特性,通过系统的应力、变形和渗流场耦合计算,研究特征工况下混合坝相互作用的形态,分析大坝施工过程和主要控制工况下各结构的渗流、应力和变形情况。分析结果表明:混合坝的渗流、变形、应力、水力劈裂均满足要求。该分析方法可为混合坝工设计和施工提供参数和依据。

基于COMSOL Multiphysics的降雨型滑坡临界降雨阈值计算模型研究——以新疆新源县喀拉海依苏滑坡隐患体为例

本文以新源县喀拉海依苏滑坡隐患体为研究案例,采用COMSOL Multiphysics数值模拟有限元软件,建立了基于非饱和渗流理论与Mohr-Coulomb准则的滑坡稳定性计算模型。根据数值模拟结果得到研究区滑坡体原始应力分布与初始孔隙压力的分布情况、在降雨入渗条件下的内部应力、有效塑性应变、塑性区、含水率、潜在滑移面等的分布情况,并计算得到滑坡体在降雨入渗条件下的安全系数。根据模型计算,滑坡体在不同降雨入渗工况下的安全系数随降雨量的增大而减小,滑坡体在连续降雨5天的临界阈值为218.82mm,根据安全系数的变化可得到滑坡体临界降雨阈值。该论文提供了一种强度折减安全系数计算降雨型黄土滑坡降雨阈值的数值模拟方法,研究结果为西北地区降雨型黄土滑坡失稳破坏的临界降雨阈值研究提供了一种有效的研究手段。

Multiphysics processes in the interfacial transition zone of fiber-reinforced cementitious composites under induced curing pressure and implications for mine backfill materials: A critical review

The mesoscale fiber-matrix interfacial transition zone(FM-ITZ) under induced curing pressure plays a key role in the effectiveness of fiber reinforcement and the engineering application of fiber-reinforced cementitious composites(FRCCs). This critical review establishes the link among induced curing pressure(i.e., external loading condition), multiphysics processes(i.e., internal governing mechanism), and interface behavior(i.e., material behavior) for FRCC materials through analysis of the state-of-the-art research findings on the FM-ITZ of FRCC materials. The following results are obtained. For the mechanical process, the induced curing pressure changes the stress state and enhances multicracking behavior, which can strengthen the FM-ITZ. For the hydraulic process, the strengthened seepage of the FM-ITZ under induced curing pressure weakens the effective stress and exaggerates the deficiency in water retention capacity between the bulk matrix and the FMITZ. For the thermal process, the induced curing pressure causes a steep temperature gradient in the FM-ITZ and thus influences the temperature evolution and thermally-induced microcracks in the FM-ITZ. For the chemical process, the induced curing pressure enhances hydration kinetics and results in the formation of additional hydration products in the FM-ITZ. Moreover, recommendations are proposed on the basis of findings from this review to facilitate the implementation of fiber reinforcement in cemented paste backfill technology.

COMSOL Multiphysics仿真软件在PT教学中的应用

PT(Physicists’Tournament)作为一种启发学生物理思维、锻炼学生动手能力、培养专业素养的创新型赛事类物理科研活动,越来越多的学生在参与过程中选择使用仿真软件作为辅助工具进行模拟计算,以完成较为复杂的开放性研究问题。由于PT实验探究具有局限性,利用软件仿真能够突破苛刻的实验条件和复杂的操作过程等限制,将实验现象转变为可视的数据结果,既是对传统实验的拓展,又能继续指导实验的开展。相比于其他软件,COMSOL Multiphysics具有易于上手、可视性强、计算功能强大等特点,对于本科学生而言具有独特的使用优势。本文从三道具有代表性的不同类型PT赛题入手,利用COMSOL Multiphysics软件进行仿真模拟,发现其具有将抽象结果可视化、弥补实际实验不足、增强探究性等应用价值。本文的研究结果为基于COMSOL Multiphysics软件开展PT问题分析与探究和培养学生创新能力提供了有益的借鉴。

Coupled multiphysical model for investigation of influence factors in the application of microbially induced calcite precipitation

The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiphysics involved in MICP,such as bacterial ureolytic activities,biochemical reactions,multiphase and multicomponent transport,and alteration of the porosity and permeability.The model incorporates multiphysical coupling effects through well-established constitutive relations that connect parameters and variables from different physical fields.It was implemented in the open-source finite element code OpenGeoSys(OGS),and a semi-staggered solution strategy was designed to solve the couplings,allowing for flexible model settings.Therefore,the developed model can be easily adapted to simulate MICP applications in different scenarios.The numerical model was employed to analyze the effect of various factors,including temperature,injection strategies,and application scales.Besides,a TBCH modeling study was conducted on the laboratory-scale domain to analyze the effects of temperature on urease activity and precipitated calcium carbonate.To understand the scale dependency of MICP treatment,a large-scale heterogeneous domain was subjected to variable biochemical injection strategies.The simulations conducted at the field-scale guided the selection of an injection strategy to achieve the desired type and amount of precipitation.Additionally,the study emphasized the potential of numerical models as reliable tools for optimizing future developments in field-scale MICP treatment.The present study demonstrates the potential of this numerical framework for designing and optimizing the MICP applications in laboratory-,prototype-,and field-scale scenarios.

基于COMSOL Multiphysics的中子扩散问题求解以及气冷微堆应用分析

基于三维有限元程序COMSOL Multiphysics的“系数形式偏微分方程接口”开发了中子扩散方程的求解模型,利用COMSOL Multiphysics的特征值和瞬态求解器分别对稳态和瞬态中子扩散方程进行了求解。通过与二维的2D-TWIGL基准题(包括稳态和瞬态工况)以及三维的3D IAEA PWR基准题的计算结果进行对比,验证了所开发中子扩散方程求解模型的正确性。针对气冷微堆堆芯进行建模,采用蒙特卡罗程序RMC生成双群和25群的群常数,利用该中子扩散求解模型开展了气冷微堆堆芯临界计算,结果分别与连续能量和多群蒙特卡罗计算参考值进行对比。结果表明:得到的有效增殖因数以及三维功率分布总体上能与对应的多群蒙特卡罗参考值较好吻合。与连续能量蒙特卡罗参考值相比,采用25能群的结果较双群划分方式更为准确。对于气冷微堆堆型,能群结构划分方式对结果精度的影响显著。采用精细能群划分能改善计算精度,但会使得求解所需资源和时间大幅上升。

基于COMSOL Multiphysics的管线用钢在3.5%NaCI溶液中的腐蚀行为研究

为了进一步了解海上平台常用管道钢的腐蚀特性,尤其是在实际工作环境下存在的高温、高Cl-腐蚀情况,本文基于大型仿真软件COMSOL Multiphysics,在3.5%NaCl(质量分数)溶液中对Q235碳钢、304L不锈钢两种管道钢材进行了仿真模拟分析,从而为海上复杂环境中钢材的使用提供参考。

基于COMSOL Multiphysics的溢流坝预应力闸墩数值分析

为分析溢流坝预应力闸墩在不同工况下的最大主应力和最大位移,给工程设计提供技术参考,以某工程溢流坝为研究对象,通过COMSOL Multiphysics建立预应力闸墩三维有限元模型,并进行数值分析,得到不同工况下预应力闸墩的位移及应力分布情况。由分析结果可知:超过混凝土抗拉强度的部位,可以通过配置非预应力钢筋来限制闸墩表面裂缝的开展。该分析方法可为类似工程预应力闸墩体系的设计和优化提供借鉴参考。

基于COMSOL Multiphysics的高压脉冲电场仿真研究

为进一步研究高压脉冲电场的作用机理,文章通过COMSOL Multiphysics仿真平台对HPEF处理装置进行三维模拟:平行极板型电场进行了三维模型建立,同时对处理装置的电场分布、温度场分布、流场分布进行多物理场仿真分析。仿真结果表明,平行极板型处理装置的电场强度分布均匀,温度基本恒定不变,空气流速接近0。这一结果与HPEF的“传递均匀、产热少、能最大限度保持食品的品质”等特色保持高度一致,为后期探究其作用机理及处理装置设计改进提供了一定的理论依据。

基于COMSOL Multiphysics超声波电机的谐振特性分析

基于COMSOL Multiphysics对超声波电机压电振子谐振特性进行了理论分析,建立了超声波电机压电振子的实体模型,仿真计算出了压电振子的谐振频率,确定超声波电动机的最佳工作频段,提出了电机与驱动电路匹配方法。试验结果表明:当对压电振子施加幅值为100V的激励电压后,软件分析和数学计算基本一致,可见仿真分析方法的可行性,为研究超声波电机谐振特性提供了一种简便的计算方法。

基于COMSOL Multiphysics的煤层气对流热采分析

COMSOL Multiphysics软件是一款以有限元法为基础,可以通过求解偏微分方程组来实现多物理场耦合计算的数值仿真软件。通过COMSOL Multiphysics软件,结合多孔介质弹性力学、渗流力学、热力学理论建立多物理场耦合模型,并借助前人成果,模拟向煤层注入200℃的水,对煤层气进行热采,计算煤层的应力场、渗流场、温度场的耦合变化规律,以及煤层气的产出量。研究结果表明:向煤层注热水60 d后,煤层温度整体达到160℃以上,煤体的渗透率基本能提高到2.1×10-12m2附近,结果证明利用对流热采新技术开发煤层气是完全可行的,开采效率极高,值得进行商业推广开发。

基于COMSOL Multiphysics的三维地质建模方法

三维地质建模具有直观、形象、便捷等优点,在地质、矿产、地下施工等领域有着突出贡献。COMSOL Multiphysics作为多物理场耦合模拟仿真软件,具备一定的三维建模能力。通过充分挖掘该软件自身潜力,结合Kriging插值方法,尝试建立了山西某井田的三维地质模型。研究结果显示,基于COMSOL Multiphysics的三维地质建模方法可实现地质体模型的缩放、旋转和平移等操作,生成地质剖切面图、透视图,展示地质体内部的各个细节。实例证明了COMSOL Multiphysics软件的三维地质建模能力及其在地质解译、矿产评估和多物理场求解等方面的应用价值。