Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with te...Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with temperature gradients,specifically the effects of adding a static carbon hoop to the outside of a CNT on the transport of a nanomotor inside the CNT.We reveal that the underlying mechanism is the uneven potential energy created by the hoops,i.e.,the hoop outside the CNT forms potential energy barriers or wells that affect mass transport inside the CNT.This fundamental control of directional mass transportation may lead to promising routes for nanoscale actuation and energy conversion.展开更多
A biconcave particle suspended in a Poiseuille flow is investigated by the multiple-relaxation-time lattice Boltzmann method with the Galilean-invariant momentum exchange method.The lateral migration and equilibrium o...A biconcave particle suspended in a Poiseuille flow is investigated by the multiple-relaxation-time lattice Boltzmann method with the Galilean-invariant momentum exchange method.The lateral migration and equilibrium of the particle are similar to the Segré-Silberberg effect in our numerical simulations.Surprisingly,two lateral equilibrium positions are observed corresponding to the releasing positions of the biconcave particle.The upper equilibrium positions significantly decrease with the increasing Reynolds number,whereas the lower ones are almost insensitive to the Reynolds number.Interestingly,the regular wave accompanied by nonuniform rotation is exhibited in the lateral movement of the biconcave particle.It can be attributed to the fact that the biconcave shape in various postures interacts with the parabolic velocity distribution of the Poiseuille flow.A set of contours illustrate the dynamic flow field when the biconcave particle has successive postures in a rotating period.展开更多
The hydrophobic nanoparticle(HNP)adsorption is a new technique of drag reduction,which changes the wettability of the porous walls of the core,generates the slip-boundary of the fluid flow and consequently enhances th...The hydrophobic nanoparticle(HNP)adsorption is a new technique of drag reduction,which changes the wettability of the porous walls of the core,generates the slip-boundary of the fluid flow and consequently enhances the oil recovery.In the present work,a seepage model with consideration of the slip effect in the micro-channels and the influence of the equivalent pore radius modified by the HNP adsorption is proposed based on the Darcy’s law.The permeability of the non-wetting phase in the porous media is calculated according to its dependence on the slip length,while the slip length is determined by a function of the contact angle and the equivalent pore radius.Numerical simulations are performed by use of the COMSOL multiphysics,and an acceptable agreement between experimental and simulation results is achieved(with an error less than 2.5%).The present model can then be used for the mechanism investigation and the prediction of the oilfield performance.展开更多
基金Project supported by the Doctoral Fund of Yanshan University (Grant No.B919)the Program of Independent Research for Young Teachers of Yanshan University (Grant No.020000534)the S&T Program of Hebei Province of China (Grant No.QN2016123)。
文摘Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with temperature gradients,specifically the effects of adding a static carbon hoop to the outside of a CNT on the transport of a nanomotor inside the CNT.We reveal that the underlying mechanism is the uneven potential energy created by the hoops,i.e.,the hoop outside the CNT forms potential energy barriers or wells that affect mass transport inside the CNT.This fundamental control of directional mass transportation may lead to promising routes for nanoscale actuation and energy conversion.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10825520 and 11162002the National Basic Research Program of China under Grant No 2012CB932400.
文摘A biconcave particle suspended in a Poiseuille flow is investigated by the multiple-relaxation-time lattice Boltzmann method with the Galilean-invariant momentum exchange method.The lateral migration and equilibrium of the particle are similar to the Segré-Silberberg effect in our numerical simulations.Surprisingly,two lateral equilibrium positions are observed corresponding to the releasing positions of the biconcave particle.The upper equilibrium positions significantly decrease with the increasing Reynolds number,whereas the lower ones are almost insensitive to the Reynolds number.Interestingly,the regular wave accompanied by nonuniform rotation is exhibited in the lateral movement of the biconcave particle.It can be attributed to the fact that the biconcave shape in various postures interacts with the parabolic velocity distribution of the Poiseuille flow.A set of contours illustrate the dynamic flow field when the biconcave particle has successive postures in a rotating period.
基金Project supported by the National Natural Science Foundation of China(Grant No.50874071)the Chinese National Programs for High Technology Research and Development(Grant No.SS2013AA061104)the Shanghai Program for Innovative Research Team in Universities,Shanghai Leading Academic Discipline Project(Grant No.S30106)
文摘The hydrophobic nanoparticle(HNP)adsorption is a new technique of drag reduction,which changes the wettability of the porous walls of the core,generates the slip-boundary of the fluid flow and consequently enhances the oil recovery.In the present work,a seepage model with consideration of the slip effect in the micro-channels and the influence of the equivalent pore radius modified by the HNP adsorption is proposed based on the Darcy’s law.The permeability of the non-wetting phase in the porous media is calculated according to its dependence on the slip length,while the slip length is determined by a function of the contact angle and the equivalent pore radius.Numerical simulations are performed by use of the COMSOL multiphysics,and an acceptable agreement between experimental and simulation results is achieved(with an error less than 2.5%).The present model can then be used for the mechanism investigation and the prediction of the oilfield performance.
