Bulk Liquid Region Research Articles

Wetting and spreading of bulk liquid and precursor film of molten AgCuTi on ultrafast laser structured surface of Ti

In order to reveal the influence of special surface structures on the wetting and spreading of Ag/Ti system and the precursor film, micro-bumps, micro-pits, micro-grooves and micro-thread surface structures were machined on a grade 2 commercially-pure Ti (TA2) surface by using ultrafast laser. In situ wetting experiments of AgCuTi filler metal on TA2 surfaces with different special structures were conducted. The results showed that the wetting morphology of AgCuTi over original TA2 surface is special double ring (small circle inside and ring outside). The special surface structures can effectively change the wetting characteristics of Ag/Ti system, including the spreading rate and the final spreading area. It also affects the structure and composition of the wetting interface. In Ag/Ti system, different components are affected to different degrees by the surface structures, resulting in uneven distribution of the bulk liquid region and the precursor film region of the wetting interface. The micro-bumps and micro-pits structures can effectively promote the wetting and spreading of AgCuTi on TA2, while micro-thread structures can inhibit its wetting spread. For the micro-grooves, the AgCuTi spreads rapidly and almost completely along the direction of the groove, while in the vertical direction, it is difficult for the AgCuTi to spread through the groove. By studying the wetting spreading process and interface behavior of molten filler metal on complex surfaces, it is expected to provide important guiding significance for using special surface microstructure to control the wetting spreading process and interface reaction of brazing system.

A multi-zone thermodynamic model for predicting LNG ageing in large cryogenic tanks

During the storage and transportation of liquefied natural gas (LNG), generation of boiloff gas (BOG) and change in the LNG composition, also known as LNG aging, are inevitable. Thus, a thermodynamic model that can accurately predict LNG aging during long-term operation is critical. This study presents a novel aging model, in which the LNG tank is divided into five zones: the vapor phase region, thermal stratification, bulk liquid region, boundary layer, and surrounding thermal insulation region. The heat and mass transport into different regions were calculated separately, and the thermal conductivity of the solid walls was considered as a function of temperature. Following model validation, simulations were performed for various thermal insulation conditions, ambient temperatures, and initial liquid compositions. From the results, the errors of the pressure, BOG rate and total heat flux could be approximated to 17, 7, and 14% respectively, for the previous models omitting the variation of thermal conductivity with temperature. As the initial methane fraction increased (i.e., N fraction decreases), the BOG rate decreased at the initial stage, while the BOG rate became less sensitive with the initial LNG composition as evaporation proceeded. Such an effect is determined by the variation in the latent heat of vaporization and total heat loss. This study can provide guidance for the design and operation of LNG storage tanks.

CFD Investigation on Movement Features of Hydrogen Bubble under Microgravity Environment

A designed cryogenic upper stage adopted liquid hydrogen and liquid oxygen (LH2/LO2) as an aerospace propellant. During a zero-gravity coast period in space, the wall heat leakage into the delivery tube could induce liquid propellant evaporation and two-phase flow phenomenon, so that a bubble discharge operation must be employed prior to engine restart. In this study, a CFD approach was utilized to numerically study the bubble discharge behaviors inside the LH2 delivery tube of the upper stage. The bubble motion properties under two different schemes, including positive acceleration effect and circulation flow operation, were analyzed and discussed. The results showed that the boiled hydrogen bubbles could increase to the size of the tube inner diameter and distribute randomly within the entire tube volume, and that, in order for the bubble to spill upward under the acceleration effect, a higher acceleration level than the needed value of acquiring liquid–vapor separation inside the propellant tank should be provided. When creating an acceleration level of 10−3 g0, most of the bubbles could spill upward within 700 s. Significantly, the bubbles could not be completely expelled in the created acceleration condition since a number of small bubbles always stagnate in the bulk liquid region. In the circulation flow operation, the gas volume reduction was mainly attributed to two mechanisms: the vapor condensation effect; and bubble discharge effect. For the case with a circulation flow rate of 0.2 kg/s, a complete bubble discharge purpose was reached within 820 s, while a large bubble stagnation in the spherical distributor occupied a remarkable proportion of the total time. In addition, both the liquid flow rate and liquid subcooling exert important effects on bubble performance. When applying a high circulation flow, the gas volume reduction is mainly due to the inertial effect of liquid flow, but the bubble stagnation in the spherical distributor still affects the total discharge time. The liquid subcooling influence on the gas volume reduction is more significant in smaller circulation flow cases. Generally, the present study provides valuable conclusions on bubble motions inside a LH2 delivery tube in microgravity, and the results could be beneficial to the sequence design of engine restart for the cryogenic upper stage.

Interfacial Forces in Free-Standing Layers of Melted Polyethylene, from Critical to Nanoscopic Thicknesses.

Molecular dynamics simulations of ultrathin free-standing layers made of melted (373.15–673.15 K) polyethylene chains, which exhibit a lower melting temperature (compared to the bulk value), were carried out to investigate the dominant pressure forces that shape the conformation of chains at the interfacial and bulk liquid regions. We investigated layer thicknesses, , from the critical limit of mechanical stability up to lengths of tens of nm and found a normal distribution of bonds dominated by slightly stretched chains across the entire layer, even at large temperatures. In the bulk region, the contribution of bond vibrations to pressure was one order of magnitude larger than the contributions from interchain interactions, which changed from cohesive to noncohesive at larger temperatures just at a transition temperature that was found to be close to the experimentally derived onset temperature for thermal stability. The interchain interactions produced noncohesive interfacial regions at all temperatures in both directions (normal and lateral to the surface layer). Predictions for the value of the surface tension, , were consistent with experimental results and were independent of . However, the real interfacial thickness—measured from the outermost part of the interface up to the point where reached its maximum value—was found to be dependent on , located at a distance of 62 Å from the Gibbs dividing surface in the largest layer studied (1568 chains or 313,600 bins); this was ~4 times the length of the interfacial thickness measured in the density profiles.

Effects of surface wettability on pool boiling process: Dynamic and thermal behaviors of dry spots and relevant critical heat flux triggering mechanism

In this paper, we investigate experimentally and numerically the influences of surface wettability on the boiling process from nucleate boiling to critical heat flux (CHF). The boiling surfaces with four different wettabilities (apparent contact angles) are examined. Using a simple optic setup, sequential phase distribution images on the boiling surfaces were acquired, and we analyzed the dynamics of microlayer, bulk liquid region, and dry spots with the processed images. The variation of surface wettability significantly affected the liquid and vapor phase behaviors on the boiling surface, such as the growth and shrinkage of the microlayer and dry spot, wetting velocity and area portion of the dry spot. As a result, the CHF increased with the surface wettability, and we found the CHF is triggered from a local dry spot where the liquid wets the spot no longer and is violently scattered by strong evaporation at the triple contact line. Our numerical simulation results, in which the three-dimensional transient heat diffusion equation was solved for the boiling substrate using the phase distribution images as boundary conditions, indicated that certain dry spots (critical dry spot) can be highly overheated under high heat flux condition, and they lead significant heat transfer degradation and, eventually, the CHF. With the numerical results and observation of the phase distribution images at the CHF conditions, we postulated the allowable wetting temperature and formulated it as a function of surface wettability through considering the balance between vapor recoil and surface tension forces. The wetting temperature increased with surface wettability, and it was confirmed by the numerical results. Finally, we proposed a qualitative relation to elucidate the influence of surface wettability on the CHF based on the heat conduction via the vapor on a critical dry spot and heat flux partitioning concept.

Plasma-liquid interfacial layer detected by in situ Raman light sheet microspectroscopy

In situ Raman microscopy has been adapted to study the plasma–water interface by applying a light sheet technique. The Raman modes of the –OO stretch of H2O2, symmetric stretch (v 1) of NO3 −, and –OH bend of water were measured simultaneously. By modulating the volume of water under detection, both the bulk liquid and interface regions have been probed with micrometer depth resolution. The plasma was a DC glow discharge generated in atmospheric-pressure air with a water cathode. In the bulk liquid, the molar concentration of aqueous NO3 − increased at a linear rate of 48 µM min−1, whereas aqueous H2O2 growth stopped at about 5 mM. The concentrations of H2O2 and NO3 − both increased when measuring at depths less than about 20 µm from the interface. The depth profile of NO3 − concentration was reconstructed, showing that the interfacial layer of NO3 − has a depth of 28 µm. The shape of the meniscus may influence the interpretation of this depth. Previous models of plasma-water interfaces have predicted interfacial layers of similar depth for short-lived aqueous species such as OH but not for long-lived species such as NO3 −.

Investigation of macrosegregation for different dendritic arm spacing, casting temperature, and thermal boundary conditions in a direct-chill casting

The study of macrosegregation for different dendritic arm spacing, casting temperature, and cooling conditions in a Direct-Chill (DC) casting was investigated in the present study. The velocity variance-elliptic relaxation ( $$ \overline{{v^{2} }} - f $$ ) turbulence model was used to account for the turbulence effect in the bulk liquid and slurry region. The thermosolutal effect was implemented in the bulk liquid and slurry flow. The Scheil’s solute redistribution model was used to account for solute partitioning at the solidification interfaces. The pressure-based segregated time-dependent solver was used in the solution method to solve the flow equations. The model validation indicates loawer transition thickness due to: (1) efficient damping of the flow in the slurry zone by the turbulence viscous forces, (2) effective handling of the kinematic wall blocking effects in the vicinity of the slurry zone, and (3) strong mixing of the turbulent fluid motion that tends to decrease the distance between the solidus and liquidus isotherm. In all the cases investigated, it was evident that the thermal boundary condition at the secondary cooling zone, casting inlet temperature and secondary Dendritic Arm Spacing (DAS) affect the segregation ratio both at the centerline and the billet surface.

Modeling mixed columnar-equiaxed solidification of Sn-10wt%Pb alloy under forced convection driven by travelling magnetic stirring

A mixed columnar-equiaxed solidification model was used to investigate the solidification benchmark experiments, as performed at SIMAP Laboratory. The first experiment case of the benchmark made under natural convection condition was successfully simulated previously. The current work is to simulate the second experiment case, i.e. the casting under travelling magnetic stirring (TMS) which is applied in the direction of natural convection to enhance the natural convection. Crystal fragmentation of columnar dendrites is assumed as the sole origin of equiaxed crystals. Through the analysis of the simulation results, deep understanding to the experimentally reported phenomena was achieved. In comparison to the first experiment case of pure natural convection condition, the TMS-enhanced convection provides a favorable condition for columnar-to-equiaxed transition (CET) by homogenizing the temperature distribution in the bulk liquid region, enhancing the fragmentation of the columnar secondary arms and the transport of the fragments to bulk liquid region. Contradicting with the previous knowledge, the TMS-enhanced convection in this experiment case does not enhance the global macrosegregation significantly. However, it strengthens the channel segregates.

Effects of bubble coalescence and breakup on CO2 absorption performance in nanoabsorbents

The complexity and dynamics of bubble coalescence and breakup have fascinated scientists for decades. In this study, we performed experiments and simulations involving successively rising bubbles in a rectangular bubble column for carbon dioxide absorption in nanoabsorbents (methanol with various concentrations of alumina nanoparticles). The variations of the bubble behavior were captured by a high-speed camera in experiments and simultaneously visualized via simulations. Firstly, we distinguished the orifice region and the bulk liquid region. The bubble diameter was determined by only the gas flow rate and orifice diameter in the orifice region; however, it changed significantly in the bulk liquid region, experiencing approximately four stages. Wake entrainment and eddy capture dominated the bubble coalescence in the bulk liquid region; however, the bubble breakup was mainly caused by eddy collision and the coalescence of two bubbles with a small surface tension force. Both coalescence and breakup were more likely to occur in liquids with a higher concentration of nanoparticles. Additionally, we considered the mass transfer coefficient in the liquid phase and found that it can be enhanced by the coalescence and breakup, through the generation of polydisperse bubble swarms. A correlated parameter was deduced that can be substituted in the Hughmark equation to predict the mass transfer coefficient of the CO2–methanol–nanoparticle system.

Plasma-Driven Reactive Species Production and Transport in a 2-D Discharge Cell

A 2-D cell was employed to study the plasma–liquid interface. Chemical probes were used to compare the chemical reactivity induced by both air and argon plasma discharges in bubbles. Methyl orange and potassium iodide-starch solutions were used to visualize the propagation of acidic and oxidative fronts into the bulk liquid beyond the interface. Acidic and oxidative fronts were observed for both air and argon plasmas, indicating that charge exchange and electron impact processes at the interface are crucial to plasma-induced reactivity in liquids. Absorption spectrophotometry of indigo trisulfonate was performed to measure the transport of oxidative species, primarily aqueous ozone, and hydroxyl radicals, from plasma to the liquid region. Chemical reactivity at the interface can be transported far into the bulk liquid region due to plasma-induced fluid flow.

A novel hybrid model combining continuum local nonequilibrium and discrete variables methods for solute trapping during rapid alloy solidification

A novel hybrid model, which combines the advantages of micro-scale discrete approach and continuum local nonequilibrium diffusion model (LNDM), has been developed to describe solute trapping and solute drag during rapid alloy solidification with non-sharp interface. The model treats the solid-liquid interface as a region with well-defined borders, which consists of n interatomic (discrete) layers. The continuum LNDM, which is presented in Acta Mater. 93 (2015) 256–263, as well as in earlier publications, describes local nonequilibrium solute diffusion in a much wider bulk liquid region. The solute partition coefficient and the solute drag energy are studied as functions of the interface velocity, the interface width and other parameters. The model predicts that the abrupt transition to partitionless and dragless solidification occurs independently of the interface width and the equilibrium partition coefficient KE at a finite interface velocity VD. The complete solute trapping velocity VD is a purely diffusion parameter, whereas the mid-transition velocity between KE and the complete solute trapping K = 1 depends on the interface width and KE.

Local thermal transport of liquid alkanes in the vicinity of α-quartz solid surfaces and thermal resistance over the interfaces: A molecular dynamics study

Thermal transport in liquid n-alkanes in the vicinity of α-quartz substrates and thermal boundary resistance between the liquid n-alkanes and the α-quartz substrates have been investigated using nonequilibrium molecular dynamics simulations. The study considers two liquid alkanes, methane and decane, and three crystal orientations of α-quartz substrate terminated with -H or -OH groups. The local thermal conductivity (LTC), defined in the same manner as with macroscopic thermal conductivity, is used to measure the efficiency of thermal energy transport of the liquids in the vicinity of the solid surface. The variations in the LTC of the liquid alkanes in the layered region next to the surface of the substrate were examined. The modeled LTC values of the alkanes were found to oscillate in the solid-liquid interface region. These fluctuations were typically proportional to the oscillations in the local density profile. The correlation between the thermal conductivity and density was linear in the bulk liquid region. The correlation between LTC and local density in the first adsorption layer is not a straightforward extension of that of the bulk liquid, which is mostly due to the specific molecular-scale ordering structure that occurs in the liquids formed by the proximity of the solid substrate. Thermal boundary resistance between the liquid alkanes and the quartz substrate was also evaluated. It was observed that thermal boundary resistance is relatively large when the in-plane molecular-scale structure in the first adsorption layer is sparse, and is lower when the liquid structure is dense in the adsorption layer.

ALE/finite element modeling of an unconfined bubble plume in periodic domain: bubble shape and oscillation analysis

This paper introduces a numerical model developed based upon the arbitrary Lagrangian–Eulerian/finite element scheme to analyze bubble plumes in a periodic domain. A spherical air bubble is immersed into a large pool of quiescent water to act as an unconfined domain. While the buoyancy force is the main physical mechanism driving the upward bubble motion, an opposite pressure gradient is imposed over the flow to balance the bulk liquid region. Periodic boundary conditions (PBC) are used together with a moving-frame technique to provide good overall analysis of the flow over a reduced computational mesh, thus reducing the computational effort. The hypotheses of a fully developed regime as well as a decomposition of the pressure field are embedded into a “one-fluid” formulation of the incompressible Navier–Stokes, which deals with the two-phase flow dynamics. Such an approach integrates a PBC-corrected semi-lagrangian treatment of the advection and a robust technique to handle the interface region in a zero-thickness fashion. At last, full three-dimensional simulations comparing the model to both numerical and experimental results concerning bubble shape factors and path oscillation for different bubble diameters, Archimedes, and Eotvos numbers are presented and discussed.

On heat transfer and evaporation characteristics in the growth process of a bubble with microlayer structure during nucleate boiling

We have previously observed and experimentally measured a microlayer formed beneath a growing bubble during nucleate pool boiling. The initial microlayer thickness was of micrometer order and increased linearly with distance from the bubble inception site. The quantitative degree of contribution of the microlayer evaporation to bubble growth was still not elucidated, although a large number of experimental studies have been conducted on the distribution and evaporation characteristics of the microlayer. To clarify the heat transfer characteristics, especially the contribution of microlayer evaporation in nucleate pool boiling, numerical simulations are performed here for two phase vapor–liquid flow induced by the growth of a single bubble using the volume of fluid method. Furthermore, a special model is proposed to combine the microlayer and bulk liquid regions, the scales of which are extremely different in the simulations. The microlayer was neglected in the volume fraction calculation, while the evaporation from the microlayer was included by applying the source terms of the basic equations for the presence of a virtual microlayer. Similar tendencies were observed between the calculated and experimental results on the variations in the microlayer radius and bubble volume. The proportion of microlayer evaporation to total bubble volume was generally in agreement with the previous results, and the ratio of microlayer evaporation to the change in the total bubble volume was approximately 40 percent.

On the phase and interface behavior along the three-phase line of ternary Lennard-Jones mixtures: a collaborative approach based on square gradient theory and molecular dynamics simulations.

This work focuses on the application of a two-way approach, where Molecular Dynamics (MD) simulations and the Square Gradient Theory (SGT) have been used for describing the phase and interface behavior of binary and ternary Lennard-Jones (LJ) mixtures, along a condition of three-phase equilibrium. The unequivocal correspondence between MD and SGT has been achieved by using the global phase diagram of binary mixtures composed by equally sized Lennard-Jones molecules, from which representative molecular parameters for Type-I, Type-II, and Type-III systems have been determined. The so selected binaries have been used then to scale the behavior of a ternary mixture characterized by complex phase equilibrium patterns. For the case of the theoretical SGT approach applied to the Lennard-Jones equation of state was used for predicting phase equilibrium and interfacial properties. In addition the corresponding MD simulations of these macroscopic properties have been conducted for the LJ potential by using equivalent molecular parameters and conditions than in the theoretical approach. Excellent agreement has been observed between the predictions obtained from theory and simulations. Particularly, our results concerning the characterization of the three phase line of a binary Type-III mixture indicate that the bulk liquid (α) and the bulk gas (G) regions are sharply separated by a bulk liquid region (β) for all the explored temperature, pressure, and concentration conditions. The structural analysis of these bulk phases reveals that a secondary liquid phase (β) perfectly wets the liquid-gas interface (α-G), as previously found for Type-II mixture [A. Mejía and L. F. Vega, J. Chem. Phys. 124, 244505 (2006)]. The exploration along the three-phase line for the ternary mixture shows good agreement between SGT and MD. Particularly, we observed the specific influence of a third component in the phase and interface behavior. From all the previous results, we conclude that the SGT applied to an EoS with appropriate mixing rules produces reliable predictions of the properties of ternary mixtures.

A molecular dynamics study on transport properties and structure at the liquid–vapor interfaces of alkanes

In this paper, self-diffusion and structure in the vicinity of liquid–vapor interfaces of several species of n-alkanes are examined using molecular dynamics simulations. The united atom NERD force field was utilized to model the alkane molecules, and the obtained properties were validated by the reported experimental results. Surface tension was calculated based on the averaged pressures, and tail corrections were implemented based on the molecular virial formulae. Present surface tension results for butane, hexane and decane are in good agreement with experimental and other simulated values. Molecular orientation and chain conformation in the interface region were examined by observing the ordering parameter and radius of gyration for decane and tetracosane. In the interface region, molecules are preferentially oriented parallel to the interface and shape of the molecules is slightly flattened in the z-direction for both decane and tetracosane. With an increase in temperature, molecules are preferentially less parallel to the interface. The Einstein relation modified for confined regions was used to obtain the self-diffusion coefficient according to migration of molecules parallel to the interface. Self-diffusion coefficient increases in the interface region for both decane and tetracosane. This increase in self-diffusion coefficient has a correlation with decrease in density. The dependency of self-diffusion coefficient on density is nonlinear in the liquid and vapor side of the interface region and is linear in between the above two regions. Influence of chain length of the alkane molecules has been studied by comparing the physical and structural quantities of decane, tetracosane and hexatriacontane at the same reduced temperature. At the same reduced temperature, self-diffusion coefficient decreases with an increase in chain length in the interface region as well as in the bulk liquid region. All three alkanes show similar tendency of ordering and chain conformation at the interface at the same reduced temperature.

Heat Transfer in the Bulk and Thin Film Fluid Regions of a Rectangular Micro Groove

Thin-film evaporation plays a key role within evaporation heat transfer. In the present study, a mathematical model was developed to determine heat transfer through both the thin-film and bulk regions of a liquid in a rectangular microgroove. The model includes the effect of contact angle and wall superheat on heat transfer through both regions. An analytical solution of the temperature distribution with in the meniscus bulk region—where the interface is dominated by surface tension―was first found via a coordinate transformation and the Galerkin method. This temperature distribution was used to determine the heat transfer rate through the bulk liquid region. Results show that the contribution of the heat transfer through the bulk region depends on the contact angle and wall superheat. The portion of heat transfer through the bulk region was found to be as high as 22 %; hence heat transfer in this region should not be neglected.

New boundary conditions for the evaporating thin-film model in a rectangular micro channel

The augmented Young–Laplace equation has been validated for modeling evaporating thin-films in the literature. However, physical conflicts still exist when it is used with the traditional rules to model the entire meniscus. New boundary conditions are developed for this model. The new conditions ensure that the center of the intrinsic meniscus is on the axis of the micro channel. The calculations indicate that the meniscus radius of the intrinsic region increases with the superheating of the heater wall. This implies a reduction of the capillary suction and a reduction of the critical heat flux for the whole micro channel. A polar disjoining pressure model is used and compared with the non-polar model. A narrow, but high heat flux, sub-region is also found at the thinner end of the intrinsic region. By considering the new boundary conditions and this sub-region, the thin-film region can be integrated smoothly with the bulk liquid region.

Superfluid 3He Confined to a Single 0.6 Micron Slab Stability and Properties of the A-Like Phase Near the Weak Coupling Limit

We present the first study of the phase diagram of a thick film of superfluid 3He confined within a nanofabricated slab geometry. This cryogenic microfluidic chamber provides a well-defined environment for the superfluid, in which both the regular geometry and surface roughness may be fully characterised. The chamber is designed with a slab thickness d=0.6 μm and 3 mm thick walls to allow pressure tuning of the effective confinement between 0 and 5.5 bar. Over this range the zero temperature superfluid coherence length, ξ0, decreases by approximately a factor of two from 77 to 40 nm. Samples have so far been cooled to 350 μK. We use nuclear magnetic resonance (NMR) to ‘finger-print’ the superfluid order parameter, with the static field applied perpendicular to the slab. To enable us to resolve high quality NMR signals from the tiny amount of superfluid 3He in the slab, we have developed a spectrometer using a two stage SQUID amplifier with unprecedented sensitivity. Simple NMR zeugmatography allows the slab signal to be unambiguously distinguished from that of a small bulk liquid region near the fill line. The measured slab transition temperature, Tcslab, shows a suppression proportional to ξ02, as expected theoretically, but the absolute suppression is less than expected. Below Tcslab, an A-like phase is stable over a significant temperature range. A transition temperature, TAX, is measured on warming from a so far unidentified phase, occurring at lower temperatures, into the A-phase. At the pressures investigated (3 to 5.5 bar) the transition appears to occur at an approximately fixed value of the effective confinement d/ξ(TAX). In this geometry we predict that the A-phase will be stable to T=0 at zero pressure.

Squeeze-Flow Electroosmotic Pumping Between Charged Parallel Plates

In the present work, the squeezing flow between two charged parallel plates is theoretically investigated, with a provision of accounting for the electric double layer overlap effects. The electroviscous effects arising from the distortion of the electric double layer flow field are investigated in detail, for different strengths of the imposed plate motion. It is revealed that there can be a significant deviation between the predictions from the present model and those obtained by employing a classical Poisson-Boltzmann equation based model. This discrepancy can be attributed to some of the over-simplified assumptions associated with the standard models that might only remain valid for large separation distances between the two plates. Many of these simplified assumptions are found to hold inappropriate in case the squeezing flow occurs in such a narrow gap that the instantaneous liquid layer thickness becomes of the same order or less than the order of the characteristic electric double layer thickness. In such cases, there is likely to be a deficit of counterions within the bulk liquid due to an excess accumulation of those in the electrical double layer. On the other hand, there may occur a surplus of coions in the bulk liquid region due to a rejection of those in the electrical double layer. As a consequence of this presence of excess net charges in the bulk liquid region, strong electro-hydrodynamic interactions are likely to occur between the squeezing motion and the electroosmotic transport, which cannot be accurately captured by the classical theory.