The development of a combined photocatalytic system with peroxymonosulfate (PMS) has great potential applications in the degradation and treatment of aqueous organic pollutants. Herein, a Co3O4-ZnO/rGO was prepared by a hydrothermal method using cobalt acetate, zinc acetate, and reduced graphene oxide (rGO) as the main raw materials. The physical and chemical characteristics of the obtained catalyst were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). The photocatalytic features and capacities of the catalytic materials to activate PMS were investigated. Co3O4-ZnO/rGO exhibited stronger photocatalytic activity and ability to activate PMS than Co3O4/rGO or ZnO/rGO, and significantly improved the ability of PMS and photocatalysis to synergistically degrade rhodamine B (RhB), with a degradation rate of 90.40% within 40 min. The mechanism of RhB degradation was proposed based on characterization of materials, evaluation of RhB degradation efficiency, and analysis of the active species involved. The unique particle/sheet structure of Co3O4-ZnO/rGO provides a large number of active sites, and the formation of heterojunctions between Co3O4 and ZnO improves carrier separation and transport in the reaction system. Our study offers a reference for designing more effective heterojunction catalysts based on the combination of PMS and photocatalytic technology.
光催化系统与过氧单硫酸盐(PMS)的组合在降解和处理水性有机污染物方面具有很大的应用前景。本文以乙酸钴、乙酸锌和还原氧化石墨烯为主要原料，采用水热法制备了Co3O4-ZnO/rGO。采用x射线衍射(XRD)、x射线光电子能谱(XPS)、扫描电子显微镜(SEM)和傅里叶变换红外(FT-IR)对催化剂的理化性质进行了分析。研究了催化材料的光催化特性和活化PMS的能力。Co3O4-ZnO/rGO表现出比Co3O4/rGO或ZnO/rGO更强的光催化活性和激活PMS的能力，显著提高了PMS和光催化协同降解rhodamine B (RhB)的能力，在40 min内降解率达到90.40%。通过材料表征、RhB降解效率评价和活性物质分析，提出了RhB降解的机理。Co3O4-ZnO/rGO独特的颗粒/片状结构提供了大量的活性位点，Co3O4和ZnO之间异质结的形成提高了反应体系中载流子的分离和输运。本研究为基于PMS与光催化技术相结合设计更有效的异质结催化剂提供了参考。
{"title":"Co3O4-ZnO/rGO catalyst preparation and rhodamine B degradation by sulfate radical photocatalysis","authors":"Zhanmei Zhang, Yi Zhang, Xilin Chen, Ziran Huang, Zuqin Zou, Huaili Zheng","doi":"10.1631/jzus.A2200490","DOIUrl":"https://doi.org/10.1631/jzus.A2200490","url":null,"abstract":"The development of a combined photocatalytic system with peroxymonosulfate (PMS) has great potential applications in the degradation and treatment of aqueous organic pollutants. Herein, a Co3O4-ZnO/rGO was prepared by a hydrothermal method using cobalt acetate, zinc acetate, and reduced graphene oxide (rGO) as the main raw materials. The physical and chemical characteristics of the obtained catalyst were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). The photocatalytic features and capacities of the catalytic materials to activate PMS were investigated. Co3O4-ZnO/rGO exhibited stronger photocatalytic activity and ability to activate PMS than Co3O4/rGO or ZnO/rGO, and significantly improved the ability of PMS and photocatalysis to synergistically degrade rhodamine B (RhB), with a degradation rate of 90.40% within 40 min. The mechanism of RhB degradation was proposed based on characterization of materials, evaluation of RhB degradation efficiency, and analysis of the active species involved. The unique particle/sheet structure of Co3O4-ZnO/rGO provides a large number of active sites, and the formation of heterojunctions between Co3O4 and ZnO improves carrier separation and transport in the reaction system. Our study offers a reference for designing more effective heterojunction catalysts based on the combination of PMS and photocatalytic technology.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"64 1","pages":"710 - 721"},"PeriodicalIF":3.2,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90339434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Ge, Jiamin He, Jin Guo, Peihao Zhang, Hao Wang, Ziqiang Ren, Xiaoling Le, Ying Wang, Yuhong Wang, Jia-wang Chen
Gravity sampling is of vital importance for sampling seabed sediments and understanding submarine sedimentary environments and resources. In this study, a new bionic sampler tube (BST) with non-smooth surface for low-disturbance and rapid sampling is presented. The BST with depressions and swellings on its surface was designed on the model of the non-smooth surface of the dung beetle. Sufficient theoretical calculations, numerical simulations, and experimental tests were carried out to study its sampling performance. The penetration depth, sample length, and frictional drag of the sampler tube were calculated. The finite element model and the coupled Eulerian-Lagrangian (CEL) method were used to analyze and compare its sampling performance. Laboratory and field gravity sampling tests were conducted and the results demonstrated the advantages of the BST in improving sampling performance and in reducing adhesion and drag.
{"title":"Research on the sampling performance of a new bionic gravity sampler","authors":"Y. Ge, Jiamin He, Jin Guo, Peihao Zhang, Hao Wang, Ziqiang Ren, Xiaoling Le, Ying Wang, Yuhong Wang, Jia-wang Chen","doi":"10.1631/jzus.A2200442","DOIUrl":"https://doi.org/10.1631/jzus.A2200442","url":null,"abstract":"Gravity sampling is of vital importance for sampling seabed sediments and understanding submarine sedimentary environments and resources. In this study, a new bionic sampler tube (BST) with non-smooth surface for low-disturbance and rapid sampling is presented. The BST with depressions and swellings on its surface was designed on the model of the non-smooth surface of the dung beetle. Sufficient theoretical calculations, numerical simulations, and experimental tests were carried out to study its sampling performance. The penetration depth, sample length, and frictional drag of the sampler tube were calculated. The finite element model and the coupled Eulerian-Lagrangian (CEL) method were used to analyze and compare its sampling performance. Laboratory and field gravity sampling tests were conducted and the results demonstrated the advantages of the BST in improving sampling performance and in reducing adhesion and drag.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"1 1","pages":"692 - 709"},"PeriodicalIF":3.2,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79828973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Inverse stochastic resonance (ISR) is a phenomenon in which the firing activity of a neuron is inhibited at a certain noise level. In this paper, the effects of potassium channel blockage on ISR in single Hodgkin-Huxley neurons and in small-world networks were investigated. For the single neuron, the ion channel noise-induced ISR phenomenon can occur only in a certain small range of potassium channel blockage ratio. Bifurcation analysis showed that this small range is the bistable region regulated by the external bias current. For small-world networks, the effect of non-homogeneous network blockage on ISR was investigated. The network blockage ratio was used to represent the proportion of potassium-channel-blocked neurons to total network neurons. It is found that an increase in network blockage ratio at small coupling strengths results in shorter ISR duration. When the coupling strength is increased, the ISR is more significant in the case of a large network blockage ratio. The ISR phenomenon is determined by the network blockage ratio, the coupling strength, and the ion channel noise. Our results will provide new perspectives on the observation of ISR in neuroscience experiments.
{"title":"Effects of potassium channel blockage on inverse stochastic resonance in Hodgkin-Huxley neural systems","authors":"Xueqing Wang, Dong Yu, Yong Wu, Qianming Ding, Tianyu Li, Ya Jia","doi":"10.1631/jzus.A2200625","DOIUrl":"https://doi.org/10.1631/jzus.A2200625","url":null,"abstract":"Inverse stochastic resonance (ISR) is a phenomenon in which the firing activity of a neuron is inhibited at a certain noise level. In this paper, the effects of potassium channel blockage on ISR in single Hodgkin-Huxley neurons and in small-world networks were investigated. For the single neuron, the ion channel noise-induced ISR phenomenon can occur only in a certain small range of potassium channel blockage ratio. Bifurcation analysis showed that this small range is the bistable region regulated by the external bias current. For small-world networks, the effect of non-homogeneous network blockage on ISR was investigated. The network blockage ratio was used to represent the proportion of potassium-channel-blocked neurons to total network neurons. It is found that an increase in network blockage ratio at small coupling strengths results in shorter ISR duration. When the coupling strength is increased, the ISR is more significant in the case of a large network blockage ratio. The ISR phenomenon is determined by the network blockage ratio, the coupling strength, and the ion channel noise. Our results will provide new perspectives on the observation of ISR in neuroscience experiments.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"306 1","pages":"735 - 748"},"PeriodicalIF":3.2,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77620257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yang Chen, Lin Jing, Tian Li, Liang Ling, Kaiyun Wang
Wheel–rail adhesion is a complex tribological problem of wheel–rail rolling contact and is closely related to the operational safety of high-speed trains. A new design concept of high-speed trains was recently proposed with an expectation of a reduction of equivalent weight and total energy consumption by installing aerodynamic wings (aero-wings) on the roof, but it was accompanied by the disadvantage of deteriorating wheel–rail adhesion performance. In this study, a comprehensive multi-body dynamics (MBD) model of the high-speed train with predesigned aero-wings is established using the commercial software SIMPACK, in which the real aerodynamic characteristics of the train are taken into account. The available adhesion and adhesion margin are employed to evaluate the wheel–rail adhesion performance. The influences of aero-wing lift, train speed, and contact conditions on the wheel–rail adhesion level are discussed. The results show that the load transfer caused by the action of aerodynamic load and braking torque was the main reason for the inconsistent adhesion condition of four wheelsets. The influences of aero-wing lift and train speed on the wheel–rail adhesion performance are coupled; the available adhesion of both motor car and trailer is negatively correlated with aero-wing lift and train speed under all contact conditions, while the variation law of adhesion margin with train speed shows differences under different contact conditions. When the wheel–rail interface was polluted by a ‘third-body medium’ such as water and oil, the wheel–rail adhesion performance was dramatically reduced and the wheelset tended to reach adhesion saturation and slide. However, track irregularity had little effect on the adhesion performance and could be ignored to save calculation time. These results are of positive significance for reducing the wheel idling or sliding phenomenon and to ensure the safe operation of high-speed trains with aero-wings.
{"title":"Numerical study of wheel–rail adhesion performance of new-concept high-speed trains with aerodynamic wings","authors":"Yang Chen, Lin Jing, Tian Li, Liang Ling, Kaiyun Wang","doi":"10.1631/jzus.A2300025","DOIUrl":"https://doi.org/10.1631/jzus.A2300025","url":null,"abstract":"Wheel–rail adhesion is a complex tribological problem of wheel–rail rolling contact and is closely related to the operational safety of high-speed trains. A new design concept of high-speed trains was recently proposed with an expectation of a reduction of equivalent weight and total energy consumption by installing aerodynamic wings (aero-wings) on the roof, but it was accompanied by the disadvantage of deteriorating wheel–rail adhesion performance. In this study, a comprehensive multi-body dynamics (MBD) model of the high-speed train with predesigned aero-wings is established using the commercial software SIMPACK, in which the real aerodynamic characteristics of the train are taken into account. The available adhesion and adhesion margin are employed to evaluate the wheel–rail adhesion performance. The influences of aero-wing lift, train speed, and contact conditions on the wheel–rail adhesion level are discussed. The results show that the load transfer caused by the action of aerodynamic load and braking torque was the main reason for the inconsistent adhesion condition of four wheelsets. The influences of aero-wing lift and train speed on the wheel–rail adhesion performance are coupled; the available adhesion of both motor car and trailer is negatively correlated with aero-wing lift and train speed under all contact conditions, while the variation law of adhesion margin with train speed shows differences under different contact conditions. When the wheel–rail interface was polluted by a ‘third-body medium’ such as water and oil, the wheel–rail adhesion performance was dramatically reduced and the wheelset tended to reach adhesion saturation and slide. However, track irregularity had little effect on the adhesion performance and could be ignored to save calculation time. These results are of positive significance for reducing the wheel idling or sliding phenomenon and to ensure the safe operation of high-speed trains with aero-wings.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"87 1","pages":"673 - 691"},"PeriodicalIF":3.2,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90391767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To investigate the re-adhesion and dynamic characteristics of the locomotive drive system with wheel slip controller, a co-simulation model of the train system was established by SIMPACK and MATLAB/SIMULINK. The uniform running and starting conditions were considered, and the influence of structural stiffness of the drive system and the wheel slip controller on the re-adhesion and acceleration performance of the locomotive was investigated. The simulation results demonstrated that the stick-slip vibration is more likely to occur in locomotives with smaller structural stiffnesses during adhesion reduction and recovery processes. There are many frequency components in the vibration acceleration spectrum of the drive system, because the longitudinal and rotational vibrations of the wheelset are coupled by the wheel–rail tangential force when stick-slip vibration occurs. In general, increasing the structural stiffness of the drive system and reducing the input energy in time are effective measures to suppress stick-slip vibration. It should also be noted that inappropriate matching of the wheel slip controller and drive system parameters may lead to electro-mechanical coupling vibration of the drive system, resulting in traction force fluctuation and poor acceleration performance.
{"title":"Determination of the dynamic characteristics of locomotive drive systems under re-adhesion conditions using wheel slip controller","authors":"Guosong Wu, Longjiang Shen, Yuan Yao, Wensheng Song, Jing-Fei Huang","doi":"10.1631/jzus.A2300158","DOIUrl":"https://doi.org/10.1631/jzus.A2300158","url":null,"abstract":"To investigate the re-adhesion and dynamic characteristics of the locomotive drive system with wheel slip controller, a co-simulation model of the train system was established by SIMPACK and MATLAB/SIMULINK. The uniform running and starting conditions were considered, and the influence of structural stiffness of the drive system and the wheel slip controller on the re-adhesion and acceleration performance of the locomotive was investigated. The simulation results demonstrated that the stick-slip vibration is more likely to occur in locomotives with smaller structural stiffnesses during adhesion reduction and recovery processes. There are many frequency components in the vibration acceleration spectrum of the drive system, because the longitudinal and rotational vibrations of the wheelset are coupled by the wheel–rail tangential force when stick-slip vibration occurs. In general, increasing the structural stiffness of the drive system and reducing the input energy in time are effective measures to suppress stick-slip vibration. It should also be noted that inappropriate matching of the wheel slip controller and drive system parameters may lead to electro-mechanical coupling vibration of the drive system, resulting in traction force fluctuation and poor acceleration performance.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"102 1","pages":"722 - 734"},"PeriodicalIF":3.2,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80618682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper puts forward a high-speed train bogie active stability method, based on frame lateral vibration control, for improving the stability and critical speed of railway vehicles at high speeds. Two inertial actuators apply active control forces to the front and rear end beams of the bogie frame. A scale model of bogie lateral dynamics is established, as well as the state space equation of the control system. Also, the multi-objective optimization is used to construct state feedback parameters, which take hunting stability and control effort into account. Furthermore, the effects of time-delay in the control system and suspension parameters on bogie hunting stability are studied. The dynamic behaviors and the stability mechanism of the bogie control system are analyzed. Finally, a 1:5 scale test rig is used to conduct a bogie active stability experiment. The results reveal that active control of frame lateral vibration can effectively improve the bogie system’s hunting stability margin at high speeds, but time-delay in the control system cannot be ignored.
{"title":"Bogie active stability simulation and scale rig test based on frame lateral vibration control","authors":"Yadong Song, Hu Li, Jun Cheng, Yuan Yao","doi":"10.1631/jzus.A2200127","DOIUrl":"https://doi.org/10.1631/jzus.A2200127","url":null,"abstract":"This paper puts forward a high-speed train bogie active stability method, based on frame lateral vibration control, for improving the stability and critical speed of railway vehicles at high speeds. Two inertial actuators apply active control forces to the front and rear end beams of the bogie frame. A scale model of bogie lateral dynamics is established, as well as the state space equation of the control system. Also, the multi-objective optimization is used to construct state feedback parameters, which take hunting stability and control effort into account. Furthermore, the effects of time-delay in the control system and suspension parameters on bogie hunting stability are studied. The dynamic behaviors and the stability mechanism of the bogie control system are analyzed. Finally, a 1:5 scale test rig is used to conduct a bogie active stability experiment. The results reveal that active control of frame lateral vibration can effectively improve the bogie system’s hunting stability margin at high speeds, but time-delay in the control system cannot be ignored.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"36 1","pages":"625 - 636"},"PeriodicalIF":3.2,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84480753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xinghong Ye, Yang Yang, Pengcheng Jiao, Zhiguo He, Lingwei Li
Underwater minirobots have attracted significant interest due to their value in complex application scenarios. Typical underwater minirobots are driven mainly by a soft or rigid actuator. However, soft actuation is currently facing challenges, including inadequate motional control accuracy and the lack of a continuous and steady driving force, while conventional rigid actuation has limited actuation efficiency, environmental adaptability, and motional flexibility, which severely limits the accomplishment of complicated underwater tasks. In this study, we developed underwater minirobots actuated by a hybrid driving method (HDM) that combines combustion-based actuators and propeller thrusters to achieve accurate, fast, and flexible underwater locomotion performance. Underwater experiments were conducted to investigate the kinematic performance of the minirobots with respect to the motion modes of rising, drifting, and hovering. Numerical models were used to investigate the kinematic characteristics of the minirobots, and theoretical models developed to unveil the mechanical principle that governs the driving process. Satisfactory agreement was obtained from comarisons of the experimental, numerical, and theoretical results. Finally, the HDM was compared with selected hybrid driving technologies in terms of acceleration and response time. The comparison showed that the minirobots based on HDM were generally superior in transient actuation ability and reliability.
{"title":"Underwater minirobots actuated by hybrid driving method","authors":"Xinghong Ye, Yang Yang, Pengcheng Jiao, Zhiguo He, Lingwei Li","doi":"10.1631/jzus.A2300056","DOIUrl":"https://doi.org/10.1631/jzus.A2300056","url":null,"abstract":"Underwater minirobots have attracted significant interest due to their value in complex application scenarios. Typical underwater minirobots are driven mainly by a soft or rigid actuator. However, soft actuation is currently facing challenges, including inadequate motional control accuracy and the lack of a continuous and steady driving force, while conventional rigid actuation has limited actuation efficiency, environmental adaptability, and motional flexibility, which severely limits the accomplishment of complicated underwater tasks. In this study, we developed underwater minirobots actuated by a hybrid driving method (HDM) that combines combustion-based actuators and propeller thrusters to achieve accurate, fast, and flexible underwater locomotion performance. Underwater experiments were conducted to investigate the kinematic performance of the minirobots with respect to the motion modes of rising, drifting, and hovering. Numerical models were used to investigate the kinematic characteristics of the minirobots, and theoretical models developed to unveil the mechanical principle that governs the driving process. Satisfactory agreement was obtained from comarisons of the experimental, numerical, and theoretical results. Finally, the HDM was compared with selected hybrid driving technologies in terms of acceleration and response time. The comparison showed that the minirobots based on HDM were generally superior in transient actuation ability and reliability.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"300 1","pages":"596 - 611"},"PeriodicalIF":3.2,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75112357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bo An, J. M. Bergadà, W. Sang, Dong Li, F. Mellibovsky
We investigate the flow inside a 2D square cavity driven by the motion of two mutually facing walls independently sliding at different speeds. The exploration, which employs the lattice Boltzmann method (LBM), extends on previous studies that had the two lids moving with the exact same speed in opposite directions. Unlike there, here the flow is governed by two Reynolds numbers (ReT, ReB) associated to the velocities of the two moving walls. For convenience, we define a bulk Reynolds number Re and quantify the driving velocity asymmetry by a parameter α. Parameter α has been defined in the range α∈[−π/4, 0] and a systematic sweep in Reynolds numbers has been undertaken to unfold the transitional dynamics path of the two-sided wall-driven cavity flow. In particular, the critical Reynolds numbers for Hopf and Neimark-Sacker bifurcations have been determined as a function of α. The eventual advent of chaotic dynamics and the symmetry properties of the intervening solutions are also analyzed and discussed. The study unfolds for the first time the full bifurcation scenario as a function of the two Reynolds numbers, and reveals the different flow topologies found along the transitional path.
{"title":"Square cavity flow driven by two mutually facing sliding walls","authors":"Bo An, J. M. Bergadà, W. Sang, Dong Li, F. Mellibovsky","doi":"10.1631/jzus.A2200447","DOIUrl":"https://doi.org/10.1631/jzus.A2200447","url":null,"abstract":"We investigate the flow inside a 2D square cavity driven by the motion of two mutually facing walls independently sliding at different speeds. The exploration, which employs the lattice Boltzmann method (LBM), extends on previous studies that had the two lids moving with the exact same speed in opposite directions. Unlike there, here the flow is governed by two Reynolds numbers (ReT, ReB) associated to the velocities of the two moving walls. For convenience, we define a bulk Reynolds number Re and quantify the driving velocity asymmetry by a parameter α. Parameter α has been defined in the range α∈[−π/4, 0] and a systematic sweep in Reynolds numbers has been undertaken to unfold the transitional dynamics path of the two-sided wall-driven cavity flow. In particular, the critical Reynolds numbers for Hopf and Neimark-Sacker bifurcations have been determined as a function of α. The eventual advent of chaotic dynamics and the symmetry properties of the intervening solutions are also analyzed and discussed. The study unfolds for the first time the full bifurcation scenario as a function of the two Reynolds numbers, and reveals the different flow topologies found along the transitional path.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"50 1","pages":"612 - 624"},"PeriodicalIF":3.2,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86490195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shiyuan Yao, Yuchao Li, Shan Tong, G. Chen, Yunmin Chen
A composite liner consisting of a geomembrane (GMB) and a geosynthetic clay liner (GCL) can be compromised by inorganic contaminants because of a defective GMB. When the composite liner with defective GMB is exposed to aggressive leachate conditions, the neglect of the chemical incompatibility of the GCL can potentially result in an underestimation of the leakage rate and flux through the composite liner. This paper proposed a numerical investigation on the effect of chemical incompatibility of GCL on the barrier performance of the composite liner with hole defect. Four cases with leachate solutions having varied cation valencies and ionic strengths were analyzed, in which the hydraulic conductivity of GCL was concentration-dependent. Both the effect of the chemical incompatibility of GCL and the mechanisms were analyzed. The incompatibility of GCL resulted in significant increases in leakage rate and flux through the composite liner by factors of up to 4.9 and 5.0, respectively. The incompatibility-affected area in GCL is located within 0.1 m from the center of the hole in the GMB. The coupled increase in the hydraulic conductivity of GCL and pore water concentration impacts the flux and leakage in a short period of time. With GCL chemical incompatibility considered, advection may dominate the contaminant transport through GCL.
{"title":"Numerical investigation of the effect of geosynthetic clay liner chemical incompatibility on flow and contaminant transport through a defective composite liner","authors":"Shiyuan Yao, Yuchao Li, Shan Tong, G. Chen, Yunmin Chen","doi":"10.1631/jzus.A2200416","DOIUrl":"https://doi.org/10.1631/jzus.A2200416","url":null,"abstract":"A composite liner consisting of a geomembrane (GMB) and a geosynthetic clay liner (GCL) can be compromised by inorganic contaminants because of a defective GMB. When the composite liner with defective GMB is exposed to aggressive leachate conditions, the neglect of the chemical incompatibility of the GCL can potentially result in an underestimation of the leakage rate and flux through the composite liner. This paper proposed a numerical investigation on the effect of chemical incompatibility of GCL on the barrier performance of the composite liner with hole defect. Four cases with leachate solutions having varied cation valencies and ionic strengths were analyzed, in which the hydraulic conductivity of GCL was concentration-dependent. Both the effect of the chemical incompatibility of GCL and the mechanisms were analyzed. The incompatibility of GCL resulted in significant increases in leakage rate and flux through the composite liner by factors of up to 4.9 and 5.0, respectively. The incompatibility-affected area in GCL is located within 0.1 m from the center of the hole in the GMB. The coupled increase in the hydraulic conductivity of GCL and pore water concentration impacts the flux and leakage in a short period of time. With GCL chemical incompatibility considered, advection may dominate the contaminant transport through GCL.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"13 1","pages":"557 - 568"},"PeriodicalIF":3.2,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79313794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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