Cover-bearing-type bucket foundation for offshore wind turbines has been paid more and more attention due to its low cost and great bearing capacity. In order to ensure the cover-bearing mode, the muddy soil inside th...Cover-bearing-type bucket foundation for offshore wind turbines has been paid more and more attention due to its low cost and great bearing capacity. In order to ensure the cover-bearing mode, the muddy soil inside the bucket foundation should be reinforced by some soil consolidation methods, such as negative pressure and electro-osmosis. Firstly, tests were conducted to obtain the reasonable current density. Meanwhile, to improve the electro-osmotic speed and effectiveness, other factors such as intermittent power and layout of electrode, were also studied in the tests. Then, the soil reinforcing tests by negative pressure combined with electro-osmosis were performed for the muddy soil consolidation inside the bucket foundation. The results showed that soil reinforcement by negative pressure was quicker and more obvious during the early phase, and electro-osmotic method can affect more range of soil by rational arrangement of electrodes. Compared with negative pressure, the electro-osmotic method was a continuous and relatively slow process of reinforcement, which was complementary to the negative pressure method. The voltage value of electro-osmosis had little effect on the muddy soil reinforcement inside the bucket foundation, and 1.5 A was chosen as the most reasonable current value for scale model testing in the electro-osmotic method.展开更多
The moisture content of subgrade soil in seasonally frozen regions is often higher than its optimum value,leading to a decline in mechanical properties and a reduction in subgrade bearing capacity.Electro-osmosis has ...The moisture content of subgrade soil in seasonally frozen regions is often higher than its optimum value,leading to a decline in mechanical properties and a reduction in subgrade bearing capacity.Electro-osmosis has shown promise as a technology for controlling subgrade moisture,but significant heterogeneity has also been observed in treated soil.This study investigates the impact of electro-osmosis on soil stiffness through a series of bender element tests of compacted clay.The effects of dry density and supply voltage on the performance of electroosmosis treatment and the layered structure and anisotropy of the soil were analyzed.The results show that electro-osmosis treatment increased the shear wave velocity of the soil by 140% compared to untreated saturated soil and by 70% compared to soil with optimum water content.It has also been found that layered compaction of soil resulted in a layered structure,with electro-osmosis having a more prominent impact on soil near the cathode,resulting in a more pronounced layered structure.Besides,electro-osmosis was found to enhance soil anisotropy,particularly near the anode.Increasing the dry density and voltage levels can help improve soil uniformity.These findings provide insights into the potential use of electro-osmosis in improving soil stiffness,which could benefit various engineering applications.展开更多
Induced-charge electro-osmosis(ICEO)is a research hotspot in bioengineering and analytical chemistry.Inflow-outflow asymmetry of ICEO was reported in the existing literatures,but systematic study on this phenomenon is...Induced-charge electro-osmosis(ICEO)is a research hotspot in bioengineering and analytical chemistry.Inflow-outflow asymmetry of ICEO was reported in the existing literatures,but systematic study on this phenomenon is insufficient.In this experimental study,we found that in strong electric fields,not only the velocity magnitude but also the vortex positions of ICEO are asymmetrical along the inflow and outflow directions because of the pronounced non-uniform surface electrokinetic transport.On the inflow and outflow directions,the amplitudes of velocities are unequal,ICEO maximum velocity positions change depending on the electric field intensity and sodium chloride(NaCl)concentration.Additionally,the distances between vortex centers are different.At NaCl solution concentration of 0.001 mol⋅L^(-1),the outflow velocity almost vanishes.The asymmetry rises with the increasing electric field intensity.The new discoveries can direct the application of microscale devices.展开更多
In this study,we proposed a numerical technique for solving time-dependent partial differential equations that arise in the electro-osmotic flowofCarreau fluid across a stationary plate based on amodified exponential ...In this study,we proposed a numerical technique for solving time-dependent partial differential equations that arise in the electro-osmotic flowofCarreau fluid across a stationary plate based on amodified exponential integrator.The scheme is comprised of two explicit stages.One is the exponential integrator type stage,and the second is the Runge-Kutta type stage.The spatial-dependent terms are discretized using the compact technique.The compact scheme can achieve fourth or sixth-order spatial accuracy,while the proposed scheme attains second-order temporal accuracy.Also,a mathematical model for the electro-osmotic flow of Carreau fluid over the stationary sheet is presented with heat and mass transfer effects.The governing equations are transformed into dimensionless partial differential equations and solved by the proposed scheme.Simulation results reveal that increasing the Helmholtz-Smoluchowski velocityUHS by 400%leads to a 60%-75%rise in peak flowvelocity,while the electro-osmotic parameter me enhances near-wall acceleration.Conversely,velocity decreases significantly with higher Weissenberg numbers,indicating the Carreau fluid’s elastic resistance and increased magnetic field strength due to improved Lorentz forces.Temperature rises with the thermal conductivity parameter 2,while higher reaction ratesγdiminish concentration and local Sherwood number values.The simulation findings show the scheme’s correctness and efficacy in capturing the complicated interactions in non-Newtonian electro-osmotic transport by revealing the notable impact of electrokinetic factors on flowbehaviour.Theproposedmodel is particularly relevant for BiologicalMicro-Electro-Mechanical Systems(BioMEMS)applications,where precise control of electro-thermal transport in non-Newtonian fluids is critical for lab-on-a-chip diagnostics,drug delivery,and micro-scale thermal management.展开更多
A mathematical study is developed for the electro-osmotic flow of a nonNewtonian fluid in a wavy microchannel in which a Bingham viscoplastic fluid model is considered.For electric potential distributions,a Poisson-Bo...A mathematical study is developed for the electro-osmotic flow of a nonNewtonian fluid in a wavy microchannel in which a Bingham viscoplastic fluid model is considered.For electric potential distributions,a Poisson-Boltzmann equation is employed in the presence of an electrical double layer(EDL).The analytical solutions of dimensionless boundary value problems are obtained with the Debye-Huckel theory,the lubrication theory,and the long wavelength approximations.The effects of the Debyelength parameter,the plug flow width,the Helmholtz-Smoluchowski velocity,and the Joule heating on the normalized temperature,the velocity,the pressure gradient,the volumetric flow rate,and the Nusselt number for heat transfer are evaluated in detail using graphs.The analysis provides important findings regarding heat transfer in electroosmotic flows through a wavy microchannel.展开更多
The moisture content of a road subgrade in cold regions will increase after freeze-thaw cycles,resulting in subgrade strength and stiffness losses.Electroosmosis is widely used in treating saturated soft soils to decr...The moisture content of a road subgrade in cold regions will increase after freeze-thaw cycles,resulting in subgrade strength and stiffness losses.Electroosmosis is widely used in treating saturated soft soils to decrease the moisture content.The induced moisture migration during electroosmosis in unsaturated soil is much more complex than that of saturated soil because of a series of nonlinear changes in soil properties.This study first uses an exponential function to characterize the relationship between electroosmotic permeability and saturation degree.Then,a one-dimensional model is developed to simulate the electroosmosis-induced moisture migration in unsaturated soil.Simulation results show that electroosmosis reduces the saturation degree of the unsaturated soil,indicating that it can be applied to subgrade dewatering.Key parameters such as soil pore size distribution coefficient,air entry value,and effective voltage significantly affect moisture migration.Electroosmotic properties of unsaturated soils are extremely important to the efficiency of electroosmosis.展开更多
Analytic expressions for speed, flux, microrotation, stress, and couple stress in a micropolar fluid exhibiting a steady, symmetric, and one-dimensional electro-osmotic flow in a uniform cylindrical microcapillary wer...Analytic expressions for speed, flux, microrotation, stress, and couple stress in a micropolar fluid exhibiting a steady, symmetric, and one-dimensional electro-osmotic flow in a uniform cylindrical microcapillary were derived under the constraint of the Debye-Hiickel approximation, which is applicable when the cross-sectional radius of the microcapillary exceeds the Debye length, provided that the zeta potential is sufficiently small in magnitude. Since the aciculate particles in a micropolar fluid can rotate without translation, micropolarity affects the fluid speed, fluid flux, and one of the two non-zero components of the stress tensor. The axial speed in a micropolar fluid intensifies when the radius increases. The stress tensor is confined to the region near the wall of the mi- crocapillary, while the couple stress tensor is uniform across the cross-section.展开更多
In the last decade,the construction of communication routes has intensified globally.As a result,many case studies have emerged related to the presence of saturated clayey soils in the foundation ground.In order to sp...In the last decade,the construction of communication routes has intensified globally.As a result,many case studies have emerged related to the presence of saturated clayey soils in the foundation ground.In order to speed up the execution of highways and railways in a safely manner,the designers use different methods for improving soft clays in terms of compressibility.The present paper aims to evaluate the efficiency of an electrochemical method used for the dewatering of a soft montmorillonite clay subgrade.The effects on the consolidation process are analyzed for the final conclusions.The advantages of the method are briefly discussed,and some potential areas for scientific research are proposed.展开更多
基金Supported by National Natural Science Foundation of China(No. 51109160)National High Technology Research and Development Program of China ("863" Program, No. 2012AA051705)International Science and Technology Cooperation Program of China (No. 2012DFA70490)
文摘Cover-bearing-type bucket foundation for offshore wind turbines has been paid more and more attention due to its low cost and great bearing capacity. In order to ensure the cover-bearing mode, the muddy soil inside the bucket foundation should be reinforced by some soil consolidation methods, such as negative pressure and electro-osmosis. Firstly, tests were conducted to obtain the reasonable current density. Meanwhile, to improve the electro-osmotic speed and effectiveness, other factors such as intermittent power and layout of electrode, were also studied in the tests. Then, the soil reinforcing tests by negative pressure combined with electro-osmosis were performed for the muddy soil consolidation inside the bucket foundation. The results showed that soil reinforcement by negative pressure was quicker and more obvious during the early phase, and electro-osmotic method can affect more range of soil by rational arrangement of electrodes. Compared with negative pressure, the electro-osmotic method was a continuous and relatively slow process of reinforcement, which was complementary to the negative pressure method. The voltage value of electro-osmosis had little effect on the muddy soil reinforcement inside the bucket foundation, and 1.5 A was chosen as the most reasonable current value for scale model testing in the electro-osmotic method.
基金supported by the National Natural Science Foundation of China(No.41971076,No.42171128)。
文摘The moisture content of subgrade soil in seasonally frozen regions is often higher than its optimum value,leading to a decline in mechanical properties and a reduction in subgrade bearing capacity.Electro-osmosis has shown promise as a technology for controlling subgrade moisture,but significant heterogeneity has also been observed in treated soil.This study investigates the impact of electro-osmosis on soil stiffness through a series of bender element tests of compacted clay.The effects of dry density and supply voltage on the performance of electroosmosis treatment and the layered structure and anisotropy of the soil were analyzed.The results show that electro-osmosis treatment increased the shear wave velocity of the soil by 140% compared to untreated saturated soil and by 70% compared to soil with optimum water content.It has also been found that layered compaction of soil resulted in a layered structure,with electro-osmosis having a more prominent impact on soil near the cathode,resulting in a more pronounced layered structure.Besides,electro-osmosis was found to enhance soil anisotropy,particularly near the anode.Increasing the dry density and voltage levels can help improve soil uniformity.These findings provide insights into the potential use of electro-osmosis in improving soil stiffness,which could benefit various engineering applications.
基金supported by the National Natural Science Foundation of China(Grant No.:51976150)the China Postdoctoral Science Foundation(Grant No.:2021M692533)the Youth Innovation Team of Shaanxi Universities.
文摘Induced-charge electro-osmosis(ICEO)is a research hotspot in bioengineering and analytical chemistry.Inflow-outflow asymmetry of ICEO was reported in the existing literatures,but systematic study on this phenomenon is insufficient.In this experimental study,we found that in strong electric fields,not only the velocity magnitude but also the vortex positions of ICEO are asymmetrical along the inflow and outflow directions because of the pronounced non-uniform surface electrokinetic transport.On the inflow and outflow directions,the amplitudes of velocities are unequal,ICEO maximum velocity positions change depending on the electric field intensity and sodium chloride(NaCl)concentration.Additionally,the distances between vortex centers are different.At NaCl solution concentration of 0.001 mol⋅L^(-1),the outflow velocity almost vanishes.The asymmetry rises with the increasing electric field intensity.The new discoveries can direct the application of microscale devices.
基金supported and funded by the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University(IMSIU)(grant number IMSIU-DDRSP2503).
文摘In this study,we proposed a numerical technique for solving time-dependent partial differential equations that arise in the electro-osmotic flowofCarreau fluid across a stationary plate based on amodified exponential integrator.The scheme is comprised of two explicit stages.One is the exponential integrator type stage,and the second is the Runge-Kutta type stage.The spatial-dependent terms are discretized using the compact technique.The compact scheme can achieve fourth or sixth-order spatial accuracy,while the proposed scheme attains second-order temporal accuracy.Also,a mathematical model for the electro-osmotic flow of Carreau fluid over the stationary sheet is presented with heat and mass transfer effects.The governing equations are transformed into dimensionless partial differential equations and solved by the proposed scheme.Simulation results reveal that increasing the Helmholtz-Smoluchowski velocityUHS by 400%leads to a 60%-75%rise in peak flowvelocity,while the electro-osmotic parameter me enhances near-wall acceleration.Conversely,velocity decreases significantly with higher Weissenberg numbers,indicating the Carreau fluid’s elastic resistance and increased magnetic field strength due to improved Lorentz forces.Temperature rises with the thermal conductivity parameter 2,while higher reaction ratesγdiminish concentration and local Sherwood number values.The simulation findings show the scheme’s correctness and efficacy in capturing the complicated interactions in non-Newtonian electro-osmotic transport by revealing the notable impact of electrokinetic factors on flowbehaviour.Theproposedmodel is particularly relevant for BiologicalMicro-Electro-Mechanical Systems(BioMEMS)applications,where precise control of electro-thermal transport in non-Newtonian fluids is critical for lab-on-a-chip diagnostics,drug delivery,and micro-scale thermal management.
文摘A mathematical study is developed for the electro-osmotic flow of a nonNewtonian fluid in a wavy microchannel in which a Bingham viscoplastic fluid model is considered.For electric potential distributions,a Poisson-Boltzmann equation is employed in the presence of an electrical double layer(EDL).The analytical solutions of dimensionless boundary value problems are obtained with the Debye-Huckel theory,the lubrication theory,and the long wavelength approximations.The effects of the Debyelength parameter,the plug flow width,the Helmholtz-Smoluchowski velocity,and the Joule heating on the normalized temperature,the velocity,the pressure gradient,the volumetric flow rate,and the Nusselt number for heat transfer are evaluated in detail using graphs.The analysis provides important findings regarding heat transfer in electroosmotic flows through a wavy microchannel.
基金the financial support from the National Key Research and Development Program of China(No.2018YFC1505306)the National Natural Science Foundation of China(No.41971076).
文摘The moisture content of a road subgrade in cold regions will increase after freeze-thaw cycles,resulting in subgrade strength and stiffness losses.Electroosmosis is widely used in treating saturated soft soils to decrease the moisture content.The induced moisture migration during electroosmosis in unsaturated soil is much more complex than that of saturated soil because of a series of nonlinear changes in soil properties.This study first uses an exponential function to characterize the relationship between electroosmotic permeability and saturation degree.Then,a one-dimensional model is developed to simulate the electroosmosis-induced moisture migration in unsaturated soil.Simulation results show that electroosmosis reduces the saturation degree of the unsaturated soil,indicating that it can be applied to subgrade dewatering.Key parameters such as soil pore size distribution coefficient,air entry value,and effective voltage significantly affect moisture migration.Electroosmotic properties of unsaturated soils are extremely important to the efficiency of electroosmosis.
文摘Analytic expressions for speed, flux, microrotation, stress, and couple stress in a micropolar fluid exhibiting a steady, symmetric, and one-dimensional electro-osmotic flow in a uniform cylindrical microcapillary were derived under the constraint of the Debye-Hiickel approximation, which is applicable when the cross-sectional radius of the microcapillary exceeds the Debye length, provided that the zeta potential is sufficiently small in magnitude. Since the aciculate particles in a micropolar fluid can rotate without translation, micropolarity affects the fluid speed, fluid flux, and one of the two non-zero components of the stress tensor. The axial speed in a micropolar fluid intensifies when the radius increases. The stress tensor is confined to the region near the wall of the mi- crocapillary, while the couple stress tensor is uniform across the cross-section.
文摘In the last decade,the construction of communication routes has intensified globally.As a result,many case studies have emerged related to the presence of saturated clayey soils in the foundation ground.In order to speed up the execution of highways and railways in a safely manner,the designers use different methods for improving soft clays in terms of compressibility.The present paper aims to evaluate the efficiency of an electrochemical method used for the dewatering of a soft montmorillonite clay subgrade.The effects on the consolidation process are analyzed for the final conclusions.The advantages of the method are briefly discussed,and some potential areas for scientific research are proposed.
