This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydra...This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydration simulation,thermodynamic calculation,and finite element analysis to examine the effects of pore solution,including effect of electrochemical potential,effect of chemical activity,and effect of mechanical interactions between ions,on the chloride effective diffusion coefficient of hydrated C3S paste.The results indicate that the effect of electrochemical potential on chloride diffusion becomes stronger with increasing hydration age due to the increase in the content of hydrated calcium silicate;as the hydration age increases,the effect of chemical activity on chloride diffusion weakens when the number of diffusible elements decreases;the effect of mechanical interactions between ions on chloride diffusion decreases with the increase of hydration age.展开更多
During nearly 200 years of development in the knowledge of Brownian motion,the Janus sphere,as a typical Brownian particle with special surface properties,has been widely studied in the past few decades.A standard Jan...During nearly 200 years of development in the knowledge of Brownian motion,the Janus sphere,as a typical Brownian particle with special surface properties,has been widely studied in the past few decades.A standard Janus sphere possesses two distinct surfaces.These two surfaces elicit different hydrodynamic interactions with ambient fluids or other interactions in response to environmental stimuli,such as chemical gradients,magnetic fields,and even light.The diffusion of Janus spheres,particularly when controlled by a remotely applied field,has inspired various applications,ranging from the design of micro-swimmers and novel procedures for probing the mechanical properties of suspensions to the fabrication of composites with enhanced performance.In this work,we report a systematic analysis of field-controlled diffusion of Janus spheres.Commencing with stochastic differential equations of motion at the microscale,we derive a coarse-grained Fokker-Planck equation at the macroscale,describing the evolution of the probability distribution function of the Janus sphere in terms of its position and orientation.Leveraging the concept of the hydrodynamic center,we derive,for the first time,explicit generalized Stokes-Einstein relations for long-time effective diffusivity,incorporating the effects of both the surface discontinuity of the Janus sphere and the external fields.The formulae enable predictions of the effective diffusivity as it varies with the slip length and characteristic angle of Janus spheres,and reveal the impact of an aligning potential field on the diffusion coefficients both parallel and perpendicular to the direction of the field.This work not only deepens the understanding of field-controlled diffusion of Janus particles,but also holds a meaningful impact on the future applications in microfluidics and related fields.展开更多
Weak turbulence often occurs during heavy pollution events in eastern China(EC).However,existing mesoscale meteorology models cannot accurately simulate turbulent diffusion under weakened turbulence,particularly under...Weak turbulence often occurs during heavy pollution events in eastern China(EC).However,existing mesoscale meteorology models cannot accurately simulate turbulent diffusion under weakened turbulence,particularly under the nocturnal stable boundary layer(SBL),often leading to significant turbulent diffusivity underestimation and surface aerosol overestimation.In this study,a new parameterization of minimum turbulent diffusivity coefficient(Kz_(min))was tested and applied to PM_(2.5)simulations in EC under SBL conditions in WRF-Chem.The original model overestimated the PM_(2.5)simulation and the simulation performance can be improved by adding Kz_(min).Sensitivity experiments revealed different ranges of available Kz_(min)values over the northern(0.8 to 1.2 m^(2)/s)and southern(1.0 to 1.5 m^(2)/s)regions of EC.The geographically related Kz_(min)was parameterized by sensible heat flux(H)and latent heat flux(LE),which also exhibited regional differences related to the climate and underlying surface.Furthermore,we assign physical significance to the parameterized formula Kz_(min)and found that our proposed Kz_(min)scheme can reasonably yield dynamic Kz_(min)values over EC.The revised Kz_(min)scheme(EXP_(NEW))enhanced the turbulent diffusion(north:0.93 m^(2)/s,south:1.10 m^(2)/s on average)in the SBL,simultaneously improving the PM_(2.5)simulations on the surface(north:65.78 to 0.67μg/m^(3);south 30.48 to 12.86μg/m^(3))and upper SBL.A process analysis showed that vertical mixing was the key process for improving PM_(2.5)simulations on the surface in EXP_(NEW).This study highlighted the importance of improving turbulent diffusion in current mesoscale models under SBL and has great significance for aerosol simulation.展开更多
In this study,the fluid flow and mixing process in an impinging stream-rotating packed bed(IS-RPB)is simulated by using a new three-dimensional computational fluid dynamics model.Specifically,the gaseliquid flow is si...In this study,the fluid flow and mixing process in an impinging stream-rotating packed bed(IS-RPB)is simulated by using a new three-dimensional computational fluid dynamics model.Specifically,the gaseliquid flow is simulated by the Euler-Euler model,the hydrodynamics of the reactor is predicted by the RNG k-εmethod,and the high-gravity environment is simulated by the sliding mesh model.The turbulent mass transfer process is characterized by the concentration variance c^(2) and its dissipation rateεc formulations,and therefore the turbulent mass diffusivity can be directly obtained.The simulated segregation index Xs is in agreement with our previous experimental results.The simulated results reveal that the fringe effect of IS can be offset by the end effect at the inner radius of RPB,so the investigation of the coupling mechanism between IS and RPB is critical to intensify the mixing process in IS-RPB.展开更多
In this research,we focus on the free-surface deformation of a one-dimensional elastic semiconductor medium as a function of magnetic field and moisture diffusivity.The problem aims to analyze the interconnection betw...In this research,we focus on the free-surface deformation of a one-dimensional elastic semiconductor medium as a function of magnetic field and moisture diffusivity.The problem aims to analyze the interconnection between plasma and moisture diffusivity processes,as well as thermo-elastic waves.The study examines the photothermoelasticity transport process while considering the impact of moisture diffusivity.By employing Laplace’s transformation technique,we derive the governing equations of the photo-thermo-elastic medium.These equations include the equations for carrier density,elastic waves,moisture transport,heat conduction,and constitutive relationships.Mechanical stresses,thermal conditions,and plasma boundary conditions are used to calculate the fundamental physical parameters in the Laplace domain.By employing numerical techniques,the Laplace transform is inverted to get complete time-domain solutions for the primary physical domains under study.Referencemoisture,thermoelastic,and thermoelectric characteristics are employed in conjunction with a graphical analysis that takes into consideration the effects of applied forces on displacement,moisture concentration,carrier density,stress due to forces,and temperature distribution.展开更多
Alumina is one of the crucial and extensively utilized refractory components.As the refractory wear due to dissolution at elevated temperatures during operation is a major threat to refractory lifespan,quantifying dis...Alumina is one of the crucial and extensively utilized refractory components.As the refractory wear due to dissolution at elevated temperatures during operation is a major threat to refractory lifespan,quantifying dissolution is important for developing cost-effective and resource-efficient refractories.This study investigated the dissolution of alumina particles in two silicate and one calcium aluminate slags at 1450,1500,and 1550°C using high-temperature confocal laser scanning microscopy(HT-CLSM).Dissolution was quantified in terms of diffusivity,with all influencing factors,including Stefan flow and bath movement,incorporated into the determination process.The trends observed in total dissolution time and diffusivity in three slags at three experimental temperatures could not be explained solely on the basis of slag basicity.Two parameters,considering the influencing factors,were introduced to explain these trends.Furthermore,the linear trend observed in Arrhenius plots of diffusivities supports the diffusivity results.Additionally,good agreement between the diffusivities of alumina in one silicate slag obtained via CLSM and rotating finger test investigations verified the reliability of the results.展开更多
基金Funded by the Natural Science Foundation of Jiangsu Province(No.BK20241529)China Postdoctoral Science Foundation(No.2024M750736)。
文摘This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydration simulation,thermodynamic calculation,and finite element analysis to examine the effects of pore solution,including effect of electrochemical potential,effect of chemical activity,and effect of mechanical interactions between ions,on the chloride effective diffusion coefficient of hydrated C3S paste.The results indicate that the effect of electrochemical potential on chloride diffusion becomes stronger with increasing hydration age due to the increase in the content of hydrated calcium silicate;as the hydration age increases,the effect of chemical activity on chloride diffusion weakens when the number of diffusible elements decreases;the effect of mechanical interactions between ions on chloride diffusion decreases with the increase of hydration age.
基金Project supported by the National Natural Science Foundation of China(Nos.12302079 and 11521202)the National Natural Science Foundation of U.S.A.(No.DMS-2306254)。
文摘During nearly 200 years of development in the knowledge of Brownian motion,the Janus sphere,as a typical Brownian particle with special surface properties,has been widely studied in the past few decades.A standard Janus sphere possesses two distinct surfaces.These two surfaces elicit different hydrodynamic interactions with ambient fluids or other interactions in response to environmental stimuli,such as chemical gradients,magnetic fields,and even light.The diffusion of Janus spheres,particularly when controlled by a remotely applied field,has inspired various applications,ranging from the design of micro-swimmers and novel procedures for probing the mechanical properties of suspensions to the fabrication of composites with enhanced performance.In this work,we report a systematic analysis of field-controlled diffusion of Janus spheres.Commencing with stochastic differential equations of motion at the microscale,we derive a coarse-grained Fokker-Planck equation at the macroscale,describing the evolution of the probability distribution function of the Janus sphere in terms of its position and orientation.Leveraging the concept of the hydrodynamic center,we derive,for the first time,explicit generalized Stokes-Einstein relations for long-time effective diffusivity,incorporating the effects of both the surface discontinuity of the Janus sphere and the external fields.The formulae enable predictions of the effective diffusivity as it varies with the slip length and characteristic angle of Janus spheres,and reveal the impact of an aligning potential field on the diffusion coefficients both parallel and perpendicular to the direction of the field.This work not only deepens the understanding of field-controlled diffusion of Janus particles,but also holds a meaningful impact on the future applications in microfluidics and related fields.
基金supported by the National Natural Science Foundation of China(Nos.92044302 and 42275115)the Natural Science Foundation of Jiangsu Province(No.BK20241711)the Postgraduate Research and Practice Innovation of Jiangsu Province Program(No.KYCX20_0952)。
文摘Weak turbulence often occurs during heavy pollution events in eastern China(EC).However,existing mesoscale meteorology models cannot accurately simulate turbulent diffusion under weakened turbulence,particularly under the nocturnal stable boundary layer(SBL),often leading to significant turbulent diffusivity underestimation and surface aerosol overestimation.In this study,a new parameterization of minimum turbulent diffusivity coefficient(Kz_(min))was tested and applied to PM_(2.5)simulations in EC under SBL conditions in WRF-Chem.The original model overestimated the PM_(2.5)simulation and the simulation performance can be improved by adding Kz_(min).Sensitivity experiments revealed different ranges of available Kz_(min)values over the northern(0.8 to 1.2 m^(2)/s)and southern(1.0 to 1.5 m^(2)/s)regions of EC.The geographically related Kz_(min)was parameterized by sensible heat flux(H)and latent heat flux(LE),which also exhibited regional differences related to the climate and underlying surface.Furthermore,we assign physical significance to the parameterized formula Kz_(min)and found that our proposed Kz_(min)scheme can reasonably yield dynamic Kz_(min)values over EC.The revised Kz_(min)scheme(EXP_(NEW))enhanced the turbulent diffusion(north:0.93 m^(2)/s,south:1.10 m^(2)/s on average)in the SBL,simultaneously improving the PM_(2.5)simulations on the surface(north:65.78 to 0.67μg/m^(3);south 30.48 to 12.86μg/m^(3))and upper SBL.A process analysis showed that vertical mixing was the key process for improving PM_(2.5)simulations on the surface in EXP_(NEW).This study highlighted the importance of improving turbulent diffusion in current mesoscale models under SBL and has great significance for aerosol simulation.
基金supported by the National Natural Science Foundation of China (22208328, 22378370 and 22108261)Fundamental Research Program of Shanxi Province(20210302124618)
文摘In this study,the fluid flow and mixing process in an impinging stream-rotating packed bed(IS-RPB)is simulated by using a new three-dimensional computational fluid dynamics model.Specifically,the gaseliquid flow is simulated by the Euler-Euler model,the hydrodynamics of the reactor is predicted by the RNG k-εmethod,and the high-gravity environment is simulated by the sliding mesh model.The turbulent mass transfer process is characterized by the concentration variance c^(2) and its dissipation rateεc formulations,and therefore the turbulent mass diffusivity can be directly obtained.The simulated segregation index Xs is in agreement with our previous experimental results.The simulated results reveal that the fringe effect of IS can be offset by the end effect at the inner radius of RPB,so the investigation of the coupling mechanism between IS and RPB is critical to intensify the mixing process in IS-RPB.
基金funded by Taif University,Taif,Saudi Arabia(TU-DSPP-2024-172).
文摘In this research,we focus on the free-surface deformation of a one-dimensional elastic semiconductor medium as a function of magnetic field and moisture diffusivity.The problem aims to analyze the interconnection between plasma and moisture diffusivity processes,as well as thermo-elastic waves.The study examines the photothermoelasticity transport process while considering the impact of moisture diffusivity.By employing Laplace’s transformation technique,we derive the governing equations of the photo-thermo-elastic medium.These equations include the equations for carrier density,elastic waves,moisture transport,heat conduction,and constitutive relationships.Mechanical stresses,thermal conditions,and plasma boundary conditions are used to calculate the fundamental physical parameters in the Laplace domain.By employing numerical techniques,the Laplace transform is inverted to get complete time-domain solutions for the primary physical domains under study.Referencemoisture,thermoelastic,and thermoelectric characteristics are employed in conjunction with a graphical analysis that takes into consideration the effects of applied forces on displacement,moisture concentration,carrier density,stress due to forces,and temperature distribution.
基金funded by the COMET program within the K2 Center “Integrated Computational MaterialProcess and Product Engineering (IC-MPPE)”, Project No. 859480+7 种基金supported by the Austrian Federal Ministries for TransportInnovationand Technology (BMVIT)Digital and Economic Affairs (BMDW)represented by the Austrian Research Funding Association (FFG)the federal states of StyriaUpper Austriaand Tyrol
文摘Alumina is one of the crucial and extensively utilized refractory components.As the refractory wear due to dissolution at elevated temperatures during operation is a major threat to refractory lifespan,quantifying dissolution is important for developing cost-effective and resource-efficient refractories.This study investigated the dissolution of alumina particles in two silicate and one calcium aluminate slags at 1450,1500,and 1550°C using high-temperature confocal laser scanning microscopy(HT-CLSM).Dissolution was quantified in terms of diffusivity,with all influencing factors,including Stefan flow and bath movement,incorporated into the determination process.The trends observed in total dissolution time and diffusivity in three slags at three experimental temperatures could not be explained solely on the basis of slag basicity.Two parameters,considering the influencing factors,were introduced to explain these trends.Furthermore,the linear trend observed in Arrhenius plots of diffusivities supports the diffusivity results.Additionally,good agreement between the diffusivities of alumina in one silicate slag obtained via CLSM and rotating finger test investigations verified the reliability of the results.
