Effect Of Interfacial Layer On Fluid Flow In Nanoporous Medium And Its Application

Nanofluidics,a developed emerging discipline in recent years,focuses on exploring the fluidic transport at nanometer scale.In this study,we propose a simple physical model of interfacial fluid layer(IFL)to account for both water adsorption and interfacial interaction between IFL and solid substrate.The results obtained from Lattice Boltzmann simulations show quantitative characterization of the vital effect of IFL on water flow inside nano-porous medium.And we have detailedly studied the effect of interfacial layer on water flow in pore-throat nanochannel with different cross-section shapes,pore-throat ratios and throat lengths.By analyzing the characterization of pore connectivity of samples with various thicknesses of IFL,we draw a conclusion that,IFL blocking is the direct reason why the low speed and permeability is.We provide a simple and effective method to study the flow phenomena in nano-porous medium using Lattice Boltzmann simulations combined with physical model,particularly to quantitatively study the interfacial layer effect in nano-porous medium.Firstly,we build a physical model of IFL,and have quantitatively studied the effect of interfacial layer on water flow in pore-throat nanochannel with different cross-section shapes,pore-throat ratios and throat lengths using LBM.It has been demonstrated that the effect of interfacial layer on the permeability of nanochannel increases sharply with decreasing the pore radius of nanochannel.Furthermore,it is found that the effect of interfacial layer on the permeability of nanochannel has close relationship with cross-section shape when the pore size is smaller than 12 nm.Besides,it has been found that both pore-throat ratio and throat length can greatly affect water flow in nanochannel,and the influence of interfacial layer on the permeability of nanochannel becomes more evident with increasing pore-throat ratio and throat length.Based on the study of water flow inside pore-throat nanochannel,we propose a simple physical model of IFL inside nanoporous medium,and calculate the permeability of nanoporous medium samples.The results show quantitative characterization of the vital effect of IFL on water flow inside nano-porous medium.After employing the IFL,the permeability of nano-porous samples declines sharply as increasing the thickness of IFL.And there is rapid rise of the relative change of permeability of nano-porous samples,manifesting the significant effect of IFL on water flow inside nano-porous samples.It is noticeable that the permeability of Sample 1 with 17.04 nm IFL is close to 0 nD,which is caused by the IFL blocking of pore space.By analyzing the characterization of pore connectivity of samples with various thicknesses of IFL,we draw a conclusion that,IFL blocking is the direct reason why the low speed and permeability is.In general,as the thickness of IFL is similar with the pore size of nanoporous medium,the effect of IFL on fluid flow inside nano-porous medium is strengthened,which confirms the necessity of considering IFL in studying nanofluidics.The achievements provide new fundamental insights into nanofluidics,and benefit to understanding the significant effect of IFL on water flow inside nano-porous medium at the quantitative level.