A novel numerical model is established to study the hydraulic fracture extend in poroelastic media with natural fractures based on the phase field method.In this new model,the poroelasticity parameter(Biot's coeff...A novel numerical model is established to study the hydraulic fracture extend in poroelastic media with natural fractures based on the phase field method.In this new model,the poroelasticity parameter(Biot's coefficient,Biot's modulus,and porosity)of rock is a function of the phasefield value.Therefore,a new phase field evolution equation is derived.The finite element numerical discretization method and Newton–Raphson(NR)iterative method are adopted to establish the corresponding numerical solution iterative scheme.The stability and correctness of the model were verified by a series of numerical simulation cases.The fluid pressure within the fracture,the fracture length,and the fracture width calculated by the model that regards the poroelasticity parameter as a constant would be larger,longer,and smaller,respectively,compared with those calculated by the model established in this study.The effect of certain formation factors and engineering factors on the intersection behavior between hydraulic fracture and natural fracture is investigated based on the established model.展开更多
Zinc metal anodes in aqueous batteries confront critical challenges from dendrite growth and side reactions at the electrode-electrolyte interface,where three phases coexist,including solid zinc metal,liquid electroly...Zinc metal anodes in aqueous batteries confront critical challenges from dendrite growth and side reactions at the electrode-electrolyte interface,where three phases coexist,including solid zinc metal,liquid electrolyte,and gaseous hydrogen bubbles.While hydrogen bubbles are conventionally perceived as detrimental byproducts,this study redefines their dual role through a phase-field model that resolves electrodeposition dynamics with multiphase interactions.Static hydrogen bubbles suppress dendrite formation beneath their shielded zones by blocking ion transport yet accelerate dendrite growth at bubble edges through electric field distortion and localized ion preservation,leading to an over 200 % increase in maximum dendrite length.Larger bubbles and closer proximity to the zinc surface amplify dendrite nucleation and elongation rates.In contrast,moving bubbles homogenize ion flux through hydrodynamic stirring,suppressing edge-localized dendrite growth.Lateral motion is more effective than vertical motion in dendrite suppression,reducing dendrite length by 53 % compared to static bubbles.Notably,oscillating bubbles combining lateral and vertical motion synergize ion blocking and preservation effects,which suppress dendrite growth more effectively,surpassing even bubble-free systems.By correlating bubble dynamics,including size,proximity,and mobility,with dendrite behavior,this work redefines hydrogen bubbles beyond mere byproducts to tunable design elements.Active bubble oscillation engineering strategies,such as ultrasonic agitation,can stabilize zinc electrodeposition by disrupting bubble adhesion and leveraging bubble dynamics.This work bridges multiphase interactions and interfacial deposition dynamics,offering pathways beyond conventional wisdom to mitigate dendrite growth and advance high-performance zinc batteries.展开更多
The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy solidification.In this work,the multiphase-field model was coupled with lattice Boltzman...The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy solidification.In this work,the multiphase-field model was coupled with lattice Boltzmann method to simulate the dendrite growth under melt convection in superalloy solidification.In the isothermal solidification simulations,zero and normal gravitational accelerations were applied to investigate the effects of gravity on the dendrite morphology and the magnitude of melt flow.The solute distribution of each alloy component along with the dendrite tip velocity during solidification was obtained,and the natural convection has been confirmed to affect the microsegregation pattern and the dendrite growth velocity.In the directional solidification simulations,two typical temperature gradients were applied,and the dendrite morphology and fluid velocity in the mushy zone during solidification were analyzed.It is found that the freckles will form when the average fluid velocity in the mushy zone exceeds the withdraw velocity.展开更多
Ferroelectric nanostructures are attracting considerable attention due to their unusual physical properties and potential applications in memory devices and nanoelectromechanical systems.It has been found that low-dim...Ferroelectric nanostructures are attracting considerable attention due to their unusual physical properties and potential applications in memory devices and nanoelectromechanical systems.It has been found that low-dimensional ferroelectrics,such as ferroelectric nanodots,ferroelectric nanotubes and ferroelectric thinfilms,exhibit polarization vortices or vortex-like domain structures due to the strong depolarizationfield and the size effect.The polarization vortex is regarded as a new toroidal order in ferroelectrics which is different from the rectilinear order of polarization.The vortex states of polarization are bistable and can be switched from one state to the other,which holds the potential application in next generation ferroelectric memories.This paper brie°y reviews the recent work on the phasefield studies of polarization vortex in ferroelectric nanostructures.The homogeneous bulk thermodynamics of ferroelectrics isfirst introduced based on the LandauDevonshire theory.To describe the inhomogeneous polarization distribution in ferroelectrics,the phasefield model including interface thermodynamics is then presented in the form of time-dependent GinzburgLandau equations.展开更多
Pore structure design is an effective strategy to tailor the thermal isolation capability of thermal barrier coatings(TBCs).Pursuing optimal porosity is crucial to balance the requirements of thermal isolation and mec...Pore structure design is an effective strategy to tailor the thermal isolation capability of thermal barrier coatings(TBCs).Pursuing optimal porosity is crucial to balance the requirements of thermal isolation and mechanical reliability since the pore structure shields thermal heat transfer but increases mechanical degradation.In this work,we investigate how thermal heat transfer couples with fracture propagation in porous TBCs by the using thermo-mechanical coupling phase field model for fracture.The simulated results show that cracks induced by thermal shock favor deflection that is sometimes perpendicular to the direction of heat flow.The thermal conductivity degradation by the transverse cracks significantly impedes thermal heat transfer,leads to enhanced reduction of the effective thermal conductivity of TBCs,decreases the average thermal stress of the substrate,and thus decreases the risk of the crack penetrating into the substrate.The numerical results demonstrate that the phase field method fully considering the thermo-mechanical interaction between cracks and pores can be a useful tool to improve the thermal isolation of porous TBCs under extreme thermal shock loadings through pore structure design.展开更多
基金supported by the National Natural Science Foundation of China(42202314)Sichuan Natural Science Foun-dation Project,China(2022NSFSC1007)Sichuan Province Science and Technology Support Program,China(2020JDJQ0059).
文摘A novel numerical model is established to study the hydraulic fracture extend in poroelastic media with natural fractures based on the phase field method.In this new model,the poroelasticity parameter(Biot's coefficient,Biot's modulus,and porosity)of rock is a function of the phasefield value.Therefore,a new phase field evolution equation is derived.The finite element numerical discretization method and Newton–Raphson(NR)iterative method are adopted to establish the corresponding numerical solution iterative scheme.The stability and correctness of the model were verified by a series of numerical simulation cases.The fluid pressure within the fracture,the fracture length,and the fracture width calculated by the model that regards the poroelasticity parameter as a constant would be larger,longer,and smaller,respectively,compared with those calculated by the model established in this study.The effect of certain formation factors and engineering factors on the intersection behavior between hydraulic fracture and natural fracture is investigated based on the established model.
基金supported by the grants from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project Nos.C5031-20G)the Guangdong Major Project of Basic and Applied Basic Research (2023B0303000002)the high level of special funds (G03034K001)。
文摘Zinc metal anodes in aqueous batteries confront critical challenges from dendrite growth and side reactions at the electrode-electrolyte interface,where three phases coexist,including solid zinc metal,liquid electrolyte,and gaseous hydrogen bubbles.While hydrogen bubbles are conventionally perceived as detrimental byproducts,this study redefines their dual role through a phase-field model that resolves electrodeposition dynamics with multiphase interactions.Static hydrogen bubbles suppress dendrite formation beneath their shielded zones by blocking ion transport yet accelerate dendrite growth at bubble edges through electric field distortion and localized ion preservation,leading to an over 200 % increase in maximum dendrite length.Larger bubbles and closer proximity to the zinc surface amplify dendrite nucleation and elongation rates.In contrast,moving bubbles homogenize ion flux through hydrodynamic stirring,suppressing edge-localized dendrite growth.Lateral motion is more effective than vertical motion in dendrite suppression,reducing dendrite length by 53 % compared to static bubbles.Notably,oscillating bubbles combining lateral and vertical motion synergize ion blocking and preservation effects,which suppress dendrite growth more effectively,surpassing even bubble-free systems.By correlating bubble dynamics,including size,proximity,and mobility,with dendrite behavior,this work redefines hydrogen bubbles beyond mere byproducts to tunable design elements.Active bubble oscillation engineering strategies,such as ultrasonic agitation,can stabilize zinc electrodeposition by disrupting bubble adhesion and leveraging bubble dynamics.This work bridges multiphase interactions and interfacial deposition dynamics,offering pathways beyond conventional wisdom to mitigate dendrite growth and advance high-performance zinc batteries.
基金financially supported by the National Key Research and Development Program of China(No.2017YFB0701503)the National Science and Technology Major Project(No.2017ZX04014001)the National Natural Science Foundation of China(No.51374137).
文摘The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy solidification.In this work,the multiphase-field model was coupled with lattice Boltzmann method to simulate the dendrite growth under melt convection in superalloy solidification.In the isothermal solidification simulations,zero and normal gravitational accelerations were applied to investigate the effects of gravity on the dendrite morphology and the magnitude of melt flow.The solute distribution of each alloy component along with the dendrite tip velocity during solidification was obtained,and the natural convection has been confirmed to affect the microsegregation pattern and the dendrite growth velocity.In the directional solidification simulations,two typical temperature gradients were applied,and the dendrite morphology and fluid velocity in the mushy zone during solidification were analyzed.It is found that the freckles will form when the average fluid velocity in the mushy zone exceeds the withdraw velocity.
基金The work was financially supported by the Natural Science Foundation of China under Grants 11002123 and 11090333Key Team of Technological Innovation of Zhejiang Province under Grant 2011R09025-07Zhejiang Provincial Natural Science Foundation under Grant R6110115.TY Zhang thank the Pao Yu Kong foundation for the partial¯nancial support.
文摘Ferroelectric nanostructures are attracting considerable attention due to their unusual physical properties and potential applications in memory devices and nanoelectromechanical systems.It has been found that low-dimensional ferroelectrics,such as ferroelectric nanodots,ferroelectric nanotubes and ferroelectric thinfilms,exhibit polarization vortices or vortex-like domain structures due to the strong depolarizationfield and the size effect.The polarization vortex is regarded as a new toroidal order in ferroelectrics which is different from the rectilinear order of polarization.The vortex states of polarization are bistable and can be switched from one state to the other,which holds the potential application in next generation ferroelectric memories.This paper brie°y reviews the recent work on the phasefield studies of polarization vortex in ferroelectric nanostructures.The homogeneous bulk thermodynamics of ferroelectrics isfirst introduced based on the LandauDevonshire theory.To describe the inhomogeneous polarization distribution in ferroelectrics,the phasefield model including interface thermodynamics is then presented in the form of time-dependent GinzburgLandau equations.
基金supported by the National Natural Science Foundation of China(Grant No.12025206)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB22040502)+2 种基金the Foundation of National Key Laboratory of Shock Wave and Denotation Physics(Grant No.6142A03192006)the National Postdoctoral Program for Innovative Talents(Grant No.BX2021284)the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2090002010)。
文摘Pore structure design is an effective strategy to tailor the thermal isolation capability of thermal barrier coatings(TBCs).Pursuing optimal porosity is crucial to balance the requirements of thermal isolation and mechanical reliability since the pore structure shields thermal heat transfer but increases mechanical degradation.In this work,we investigate how thermal heat transfer couples with fracture propagation in porous TBCs by the using thermo-mechanical coupling phase field model for fracture.The simulated results show that cracks induced by thermal shock favor deflection that is sometimes perpendicular to the direction of heat flow.The thermal conductivity degradation by the transverse cracks significantly impedes thermal heat transfer,leads to enhanced reduction of the effective thermal conductivity of TBCs,decreases the average thermal stress of the substrate,and thus decreases the risk of the crack penetrating into the substrate.The numerical results demonstrate that the phase field method fully considering the thermo-mechanical interaction between cracks and pores can be a useful tool to improve the thermal isolation of porous TBCs under extreme thermal shock loadings through pore structure design.
