A mathematical model based on Darcy’s law and electroosmosis equation in porous media is developed and two parameters named electroosmosis coefficient K, and relative electroosmosis coefficient Kre are used to calcul...A mathematical model based on Darcy’s law and electroosmosis equation in porous media is developed and two parameters named electroosmosis coefficient K, and relative electroosmosis coefficient Kre are used to calculate the curves of Ke and Krevs. water saturation whick are employed to estimate the effect of electroosmosis on water displacing oil process in sandstone cores. Under the conditions of constant injection rate displacement and constant electrical potential gradient, the method to calculate parameters K. and K. at different water saturation is developed and unsteadystate displacement experin.ental data under the effect of electroosmosis are used to determine the Parameter values. The results show that K, and K, are increased firstly with increasing water saturation and then decreased. This trend shows the inter-relationship between electroosmosis and the water displacing oil process. Finally, application of the model to ECMP mechauics studies and ac-tual reservoirs is analyzed in this peper.展开更多
Based on the electric double layer (EDL) theory and the momentum equation governing the electroosmosis flow, this paper presents an analytical solution to the periodical electroosmosis with a parallel straight capilla...Based on the electric double layer (EDL) theory and the momentum equation governing the electroosmosis flow, this paper presents an analytical solution to the periodical electroosmosis with a parallel straight capillary bundle model of reservoir rocks to reveal the microscopic mechanism of the electroosmotic flows in rocks. The theory shows that both the frequency dispersion characteristics of the macroscopic electroosmotic Darcy velocity in unsealed rocks and the electroosmotic pressure coefficient in sealed rocks depend on the porosity and electrochemical properties of reservoir rocks. The mathematical simulation indicates that the distribution of the periodical electroosmotic velocity is wavelike in the rock pore. The greater the porosity is, the greater electroosmotic the Darcy velocity and the smaller electroosmotic pressure coefficient are generated. The module values of the electroosmotic Darcy velocity and the electroosmotic pressure coefficient increase with the decreasing solution concentration or the increasing cation exchange capacity without affecting the phase of the electroosmotic Darcy velocity.展开更多
The influence of water boundary conditions on pore pressure was studied by one-dimensional electroosmotic consolidation test, and the effects of electroosmosis, pore water pressure,settlement and electroosmotic flow w...The influence of water boundary conditions on pore pressure was studied by one-dimensional electroosmotic consolidation test, and the effects of electroosmosis, pore water pressure,settlement and electroosmotic flow were monitored and analyzed.The results show that the boundary conditions of electroosmotic water have a significant effect on the pore water pressure and improving effect. Negative pore water pressure without auxiliary water is far greater than the replenishment. The measured data show that improvements in experiments without replenishment are also better. The calculation of Esrig solution of the pore water pressure is consistent with the measurement data in the watersupplementing test and is very different from the measurement data in the test without rehydration. Considering the impact of water boundary conditions is the key to electroosmosis experiments and applications.展开更多
The process of lubricant penetration into frictional interfaces has not been fully established,hence compromising their tribological performance.In this study,the penetration characteristics of deionized water(DI wate...The process of lubricant penetration into frictional interfaces has not been fully established,hence compromising their tribological performance.In this study,the penetration characteristics of deionized water(DI water)containing an electroosmotic suppressant(cetyltrimethylammonium bromide(CTAB))and an electroosmotic promoter(sodium lauriminodipropionate(SLI)),were investigated using steel-onsteel friction pairs.The results indicated that the lubricant with electroosmotic promoter reduced the coefficient of friction and wear scar diameter,whereas that with an electroosmotic suppressant exhibited an opposite behavior compared with DI water.The addition of SLI promoted the penetration of the DI water solution,thus resulting in the formation of a thick lubricating film of iron oxide at the sliding surface.This effectively reduced the abrasion damage,leading to a lower coefficient of friction and wear loss.展开更多
The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro fl...The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro flow control elements which have been explored in parallel with the rapid developments in micro fabrication technologies, the present focus is on its application to biomimetics. As soil animals (in fact all living creatures) such as earthworms and dung beetles carry bioelectricity, the relative movement between the creatures and the surrounding soil which is a multi-component medium with moist content will generate electrophoresis or electroosmosis forces. Such forces drive the ionized moist content, normally water, to migrate from positive to negative poles under the action of electric double layer (EDL) effect, and effectively reduce the adhesion or drag.Predicting the electroosmotically driven flow in the vicinity of biological and animal surfaces is a key problem of drag/adhesion reduction and biomimetics design. The aim of this article is to demonstrate how the theory of electroosmotically driven flow has developed and to describe its broader significance for anti adhesion of soil animals and biomimetics design of soil machinery tools.展开更多
We investigate the effect of curvature of the tip and the convexity of an electrode on the localization of suspended particles under the combined effect of dielectrophoresis and AC electroosmosis through simulations u...We investigate the effect of curvature of the tip and the convexity of an electrode on the localization of suspended particles under the combined effect of dielectrophoresis and AC electroosmosis through simulations using COMSOL Multiphysics. A systematic analysis of the parameters defining the convexity of the electrode—the radius of the tip and the apex angle shows that suspended particles can be trapped closely to the electrode edges for comparatively larger tip radii and apex angles. This in turn should favour the trapping of polarizable molecules between the electrodes only if the fluid velocities at the vortices are not very strong.展开更多
By the two-scale homogenization approach we justify a two-scale model of ion transport through a layered membrane, with flows being driven by a pressure gradient and an external electrical field. By up-scaling, the el...By the two-scale homogenization approach we justify a two-scale model of ion transport through a layered membrane, with flows being driven by a pressure gradient and an external electrical field. By up-scaling, the electroosmotic flow equations in horizontal thin slits separated by thin solid layers are approximated by a homogenized system of macroscale equations in the form of the Poisson equation for induced vertical electrical field and Onsager's reciprocity relations between global fluxes (hydrodynamic and electric) and forces (horizontal pressure gradient and external electrical field). In addition, the two-scale approach provides macroscopic mobility coefficients in the Onsager relations. On this way, the cross-coupling kinetic coefficient is obtained in a form which does involves the ζ -potential among the data provided the surface current is negligible.展开更多
This review article presents an overview on the application of electrohydrodynamics and Joule heating effects in microfluidic chips.A brief introduction of microfluidic chips and a classification of electrohydrodynami...This review article presents an overview on the application of electrohydrodynamics and Joule heating effects in microfluidic chips.A brief introduction of microfluidic chips and a classification of electrohydrodynamics as well as the applications in microfluidic devices are first given.Then basic theories and governing equations of classical electromagnetics are summarized and electroviscous effects in pressure driven flows in a microchannel are presented.Principles and applications of DC electrokinetics,including DC electroosmotic flow,DC electrophoresis,as well as principles of AC electrokinetics,including AC electroosmotic flow and dielectrophoresis are also reviewed.Finally,Joule heating effects in both DC and AC electrokinetics,especially the newly discovered electrothermal flow,are summaried.展开更多
文摘A mathematical model based on Darcy’s law and electroosmosis equation in porous media is developed and two parameters named electroosmosis coefficient K, and relative electroosmosis coefficient Kre are used to calculate the curves of Ke and Krevs. water saturation whick are employed to estimate the effect of electroosmosis on water displacing oil process in sandstone cores. Under the conditions of constant injection rate displacement and constant electrical potential gradient, the method to calculate parameters K. and K. at different water saturation is developed and unsteadystate displacement experin.ental data under the effect of electroosmosis are used to determine the Parameter values. The results show that K, and K, are increased firstly with increasing water saturation and then decreased. This trend shows the inter-relationship between electroosmosis and the water displacing oil process. Finally, application of the model to ECMP mechauics studies and ac-tual reservoirs is analyzed in this peper.
基金supported by the National Natural Science Foundation of China (No. 41174101)the Natural Science Foundation of Shandong Province of China (No. ZR2011DM002)
文摘Based on the electric double layer (EDL) theory and the momentum equation governing the electroosmosis flow, this paper presents an analytical solution to the periodical electroosmosis with a parallel straight capillary bundle model of reservoir rocks to reveal the microscopic mechanism of the electroosmotic flows in rocks. The theory shows that both the frequency dispersion characteristics of the macroscopic electroosmotic Darcy velocity in unsealed rocks and the electroosmotic pressure coefficient in sealed rocks depend on the porosity and electrochemical properties of reservoir rocks. The mathematical simulation indicates that the distribution of the periodical electroosmotic velocity is wavelike in the rock pore. The greater the porosity is, the greater electroosmotic the Darcy velocity and the smaller electroosmotic pressure coefficient are generated. The module values of the electroosmotic Darcy velocity and the electroosmotic pressure coefficient increase with the decreasing solution concentration or the increasing cation exchange capacity without affecting the phase of the electroosmotic Darcy velocity.
基金National Natural Science Foundation of China(No.51578214)Chinese Ministry of Education,China(No.GH201304)
文摘The influence of water boundary conditions on pore pressure was studied by one-dimensional electroosmotic consolidation test, and the effects of electroosmosis, pore water pressure,settlement and electroosmotic flow were monitored and analyzed.The results show that the boundary conditions of electroosmotic water have a significant effect on the pore water pressure and improving effect. Negative pore water pressure without auxiliary water is far greater than the replenishment. The measured data show that improvements in experiments without replenishment are also better. The calculation of Esrig solution of the pore water pressure is consistent with the measurement data in the watersupplementing test and is very different from the measurement data in the test without rehydration. Considering the impact of water boundary conditions is the key to electroosmosis experiments and applications.
基金The authors gratefully acknowledge the support of the National Natural Science Foundation of China(No.51775507)the Natural Science Foundation of Zhejiang Province(No.LY19E050006).
文摘The process of lubricant penetration into frictional interfaces has not been fully established,hence compromising their tribological performance.In this study,the penetration characteristics of deionized water(DI water)containing an electroosmotic suppressant(cetyltrimethylammonium bromide(CTAB))and an electroosmotic promoter(sodium lauriminodipropionate(SLI)),were investigated using steel-onsteel friction pairs.The results indicated that the lubricant with electroosmotic promoter reduced the coefficient of friction and wear scar diameter,whereas that with an electroosmotic suppressant exhibited an opposite behavior compared with DI water.The addition of SLI promoted the penetration of the DI water solution,thus resulting in the formation of a thick lubricating film of iron oxide at the sliding surface.This effectively reduced the abrasion damage,leading to a lower coefficient of friction and wear loss.
文摘The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro flow control elements which have been explored in parallel with the rapid developments in micro fabrication technologies, the present focus is on its application to biomimetics. As soil animals (in fact all living creatures) such as earthworms and dung beetles carry bioelectricity, the relative movement between the creatures and the surrounding soil which is a multi-component medium with moist content will generate electrophoresis or electroosmosis forces. Such forces drive the ionized moist content, normally water, to migrate from positive to negative poles under the action of electric double layer (EDL) effect, and effectively reduce the adhesion or drag.Predicting the electroosmotically driven flow in the vicinity of biological and animal surfaces is a key problem of drag/adhesion reduction and biomimetics design. The aim of this article is to demonstrate how the theory of electroosmotically driven flow has developed and to describe its broader significance for anti adhesion of soil animals and biomimetics design of soil machinery tools.
文摘We investigate the effect of curvature of the tip and the convexity of an electrode on the localization of suspended particles under the combined effect of dielectrophoresis and AC electroosmosis through simulations using COMSOL Multiphysics. A systematic analysis of the parameters defining the convexity of the electrode—the radius of the tip and the apex angle shows that suspended particles can be trapped closely to the electrode edges for comparatively larger tip radii and apex angles. This in turn should favour the trapping of polarizable molecules between the electrodes only if the fluid velocities at the vortices are not very strong.
文摘By the two-scale homogenization approach we justify a two-scale model of ion transport through a layered membrane, with flows being driven by a pressure gradient and an external electrical field. By up-scaling, the electroosmotic flow equations in horizontal thin slits separated by thin solid layers are approximated by a homogenized system of macroscale equations in the form of the Poisson equation for induced vertical electrical field and Onsager's reciprocity relations between global fluxes (hydrodynamic and electric) and forces (horizontal pressure gradient and external electrical field). In addition, the two-scale approach provides macroscopic mobility coefficients in the Onsager relations. On this way, the cross-coupling kinetic coefficient is obtained in a form which does involves the ζ -potential among the data provided the surface current is negligible.
基金Supported by the National Natural Science Foundation of China(Grant No.50536010)the Shanghai Municipal Science&Technology Committee through Key Fundamental(Grant No.08JC1411100)
文摘This review article presents an overview on the application of electrohydrodynamics and Joule heating effects in microfluidic chips.A brief introduction of microfluidic chips and a classification of electrohydrodynamics as well as the applications in microfluidic devices are first given.Then basic theories and governing equations of classical electromagnetics are summarized and electroviscous effects in pressure driven flows in a microchannel are presented.Principles and applications of DC electrokinetics,including DC electroosmotic flow,DC electrophoresis,as well as principles of AC electrokinetics,including AC electroosmotic flow and dielectrophoresis are also reviewed.Finally,Joule heating effects in both DC and AC electrokinetics,especially the newly discovered electrothermal flow,are summaried.
