Measurement of density,sound velocity,surface tension,and viscosity of freely suspended supercooled liquids

Noncontact methods have been implemented in conjunction with levitation techniques to carry out the measurement of the macroscopic properties of liquids significantly cooled below their nominal melting point. Free suspension of the sample and remote methods allow the deep excursion into the metastable liquid state and the determination of its thermophysical properties. We used this approach to investigate common substances such as water,v-terphenyl. succinonitrile, as well as higher temperature melts such as molten indium, aluminum, and other metals. Although these techniques have thus far involved ultrasonic, eletromagnetic, and more recently electrostatic levitation, we restrict our attention to ultrasonic methods in this paper. The resulting magnitude of maximum thermal supercooling achieved has ranged between 10% and 15% of the absolute temperature of the melting point for the materials mentioned above. The methods for measuring the physical properties have been mostly novel approaches, and the typical accuracy achieved has not yet matched the standard equivalent techniques involving contained samples and invasive probing. They are currently being refined, however, as the levitation techniques become more widespread and as we gain a better understanding of the physics of levitated liquid samples.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–34, 1994, Boulder, Colorado, U.S.A.     

Evolution of nonlinear interfacial structure induced by combined effect of Rayleigh-Taylor and Kelvin-Helmholtz instability

The nonlinear evolution of two fluid interfacial structures such as bubbles and spikes arising due to the combined action of Rayleigh-Taylor and Kelvin-Helmholtz instability is investigated. Using Layzer's model analytic expressions for the asymptotic value of the combined growth rate are obtained in both cases for spikes and bubbles. However, if the overlying fluid is of lower density the interface perturbation behaves in different ways. Depending on the magnitude of the velocity shear associated with Kelvin-Helmholtz instability both the bubble and spike amplitude may simultaneously grow monotonically (instability) or oscillate with time.     

The surface tension meniscus of liquid helium

A technique is described for calculating the shape of the surface tension meniscus at a vertical wall, in the presence of Van der Waals forces. The method of analytic continuation is used to compute a solution of the relevant differential equation. Results (believed accurate to better than 0.5%) are presented for He³ and for He⁴ at a variety of film flow rates. It is found that the shape of the classical meniscus remains unaltered over most of its length, but it is displaced horizontally relative to the wall by a flow dependent amount. The results are contrasted with those from a previous calculation.     

Remarks on tension instability of Eulerian and Lagrangian corrected smooth particle hydrodynamics (CSPH) methods

The paper discusses the problem of tension instability of particle‐based methods such as smooth particle hydrodynamics (SPH) or corrected SPH (CSPH). It is shown that tension instability is a property of a continuum where the stress tensor is isotropic and the value of the pressure is a function of the density or volume ratio. The paper will show that, for this material model, the non‐linear continuum equations fail to satisfy the stability condition in the presence of tension. Consequently, any discretization of this continuum will result in negative eigenvalues in the tangent stiffness matrix that will lead to instabilities in the time integration process. An important exception is the 1‐D case where the continuum becomes stable but SPH or CSPH can still exhibit negative eigenvalues. The paper will show that these negative eigenvalues can be eliminated if a Lagrangian formulation is used whereby all derivatives are referred to a fixed reference configuration. The resulting formulation maintains the momentum preservation properties of its Eulerian equivalent. Finally a simple 1‐D wave propagation example will be used to demonstrate that a stable solution can be obtained using Lagrangian CSPH without the need for any artificial viscosity. Copyright © 2001 John Wiley & Sons, Ltd.     

The prediction of surface tension in mixtures of cryogenic liquids

Recently we showed how a fluid model for predicting thermodynamic properties could be used to correlate surface tension of organic liquids. We apply the model here to predict the surface tension of the cryogenic binary mixtures of methane, carbon monoxide, argon and nitrogen.⁵     

Magneto-thermo-visco-elastic waves in an initially stressed conducting layer

The aim of this paper is to investigate magneto-thermo-viscoelastic surface waves in electrically and thermally conducting layers involving time rates of strain and stress of ordern, the media being under an initial stress in the nature of hydrostatic tension or compression. The theory of magneto-thermo-visco-elastic surface waves in the conducting medium involving strain rate and stress rate ofnth order is derived under initial stress. This theory is then employed to obtain wave velocity equations in specific cases. Results obtained in the above cases reduce to well-known classical results when additional fields are absent.     

表面张力作用下抗粘附的微齿轮结构设计原理研究

粘附是微机械中最常见的一种失效现象,一般的微机械结构都极力避免粘附的出现．表面张力是引起微结构粘附的最主要原因．深入研究了表面张力作用下使构件产生粘附的物理机理．以多晶硅微齿轮为例,考虑其在表面张力作用下发生的粘附现象,推导出表面张力作用下抗粘附多晶硅微齿轮结构参数设计公式．结果表明,微齿轮产生粘附与材料特性（弹性特性、表面特性）、微齿轮结构参数（半径、齿宽）、微齿轮与基体之间的间隙有关．     

复合驱油体系的界面剪切粘度与界面张力研究

应用界面粘弹性测定仪和界面张力仪,测定了碱、表面活性剂和聚合物三元复合驱油体系的油／水界面剪切粘度和界面张力。实验表明,在一般情况下,碱和表面活性剂的降低界面张力作用与提高界面剪切粘度作用相对应。聚合物HPAM大多数情况下都使界面张力略有升高。且可使极低的界面剪切粘度升高,很高的界面剪切粘度降低。     

Simultaneous measurement of surface tension and kinematic viscosity using thermal fluctuations

We have developed a surface laser-light scattering apparatus to measure simultaneously surface tension and kinematic viscosity. In this method, we can obtain the surface properties by the laser heterodyne detection of light scattered from thermally excited capillary waves (called ripplon), which are typically of low amplitude (1 nm) and a characteristic wavelength (100m). Two gratings (d=100 and 200m) were employed to select the wave number of the capillary waves and to produce a reference beam for heterodyne detection. It was found through an experimental study on water that this contact-free method has considerable potential for application to measurements under extreme conditions such as high temperatures and high pressures.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

未变性胶原生物表面活性剂的表面张力及其表面吸附

研究了一种未变性胶原生物表面活性剂(CBS)水溶液的表面张力和表面吸附性质。结果表明,CBS水溶液的表面张力随CBS浓度的增大而降低,最终趋于平缓,达到55.92 mN/m。在等电点附近,CBS表面静电荷降低,使其表面张力显著降低。在低温下,CBS溶液的表面活性较好,当温度继续升高(35℃),由于变性作用,CBS溶液的表面张力急剧增大。CBS水溶液的吸附属于Langmiur型吸附,根据γ-lgC、Γ-C以及C/Γ-C拟合曲线计算得到饱和吸附量相似,分别为1.86×10-10,1.97×10-10和2.03×10-10 mol/cm2。吸附自由能为-3.53kJ/mol,表明其在标准状态下可以自发进行。     

Fully implicit finite element method for the modeling of free surface flows with surface tension effect

A new approach based on the use of the Newton and level set methods allows to follow the motion of interfaces with surface tension immersed in an incompressible Newtonian fluid. Our method features the use of a high‐order fully implicit time integration scheme that circumvents the stability issues related to the explicit discretization of the capillary force when capillary effects dominate. A strategy based on a consistent Newton–Raphson linearization is introduced, and performances are enhanced by using an exact Newton variant that guarantees a third‐order convergence behavior without requiring second‐order derivatives. The problem is approximated by mixed finite elements, while the anisotropic adaptive mesh refinements enable us to increase the computational accuracy. Numerical investigations of the convergence properties and comparisons with benchmark results provide evidence regarding the efficacy of the methodology. The robustness of the method is tested with respect to the standard explicit method, and stability is maintained for significantly larger time steps compared with those allowed by the stability condition. Copyright © 2016 John Wiley & Sons, Ltd.     

Viscosity,thermal conductivity,and surface tension of high-temperature melts

High-temperature melts are substances which are solids at room temperature and liquids at high temperatures. They include liquid metals, molten salts, and other melts such as molten semiconductor materials. Although they show scientifically interesting behavior and have industrially important characteristics, the thermophysical properties of these substances at high temperature are not sufficiently known due to experimental difficulties. Many melts show strong chemical activity and therefore are corrosive to materials of container and sensors. Applicable sensors are limited also because of the high temperature and the electrical conductivity of melts. In this paper the present status of available data for the viscosity, the thermal conductivity, and the surface tension of high-temperature melts is reviewed. Limited experimental information is available and these properties are difficult to predict theoretically. The transport properties are important for predicting heat transfer and flow patterns. For the prediction of the behavior of melts under microgravity condition, the temperature dependence of the surface tension plays a major role.Paper presented at the Second U.S.-Japan Joint Seminar on Thermophysical Properties, June 23, 1988, Gaithersburg, Maryland, U.S.A.     

The influence of variable surface tension on capillary-gravity waves

Periodic gravity-capillary waves propagating at a constant velocity at the surface of a fluid of infinite depth are considered. The surface tension is assumed to vary along the free surface. A numerical procedure is presented to solve the problem with an arbitrary distribution of surface tension on the free surface. It is found that there are many different families of solutions. These solutions generalize the classical theory of gravity-capillary waves with constant surface tension. An asymptotic solution is presented for a particular distribution of variable surface tension.     

The effect of temperature and polymer concentration on dynamic surface tension and wetting ability of hydroxypropylmethylcellulose solutions

The purpose of the present study was to evaluate quantitatively the changes of dynamic surface tension and contact angle of hydroxypropylmethylcellulose (HPMC) aqueous solutions as a function of temperature and polymer concentration of the examined solutions. HPMC aqueous solutions of different concentrations (1%, 2%, 3%, 4% w/w) were prepared without plasticizer and with 1% w/w Lutrol F127. Dynamic surface tension of the prepared solutions was determined by the Du Nouy ring method of the KSV Sigma 70 computer-controlled and programmable tensiometer. The dynamic contact angle of Avicel PH-101 tablets was measured against HPMC solutions of various concentrations by the plate method of the KSV Sigma 70 tensiometer. The obtained results indicate that dynamic surface tension measurement can be applied for the accurate determination of the thermal gelation temperature of the prepared HPMC solutions. With increasing concentration of HPMC, dynamic contact angle values of solutions also increased, thus decreasing the spreading behavior on the surface of Avicel tablets.     

表面张力和凝胶时间对膜结构的影响

研究了表面张力和凝胶时间对膜结构的影响。结果表明，表面张力对膜皮层结构有影响，凝胶时间则对整个膜结构都有影响。组分透过膜的阻力是由膜材料与组分间的诸如氢键、静电、极性、非极性等各种作用力形成势能场及形状阻力，动力则是待透组分的热运动，因此，膜的单孔分离系数随孔径的增大存在一极大值，单孔通量则随孔径的增大而增大。     

液体表面张力系数与浓度的关系实验研究

为探究液体表面张力与液体浓度的关系,利用压阻式力敏传感器,采用拉脱法,测试室温下水及不同浓度的蔗糖水、盐水、酒精、肥皂水的表面张力系数。实验结果表明:蔗糖水和盐水的表面张力系数随浓度的增大而增加,而酒精、肥皂水的表面张力系数随浓度的增大而减小。     

Finite-size effects in surface tension: Thermodynamics and the Gaussian interface model

It has been suggested by Kayser that finite-size effects associated with capillary waves might play a significant role in some surface tension measurements; for capillary rise between plates a distance D apart, an effect varying as 1/D and apparently observable in measurements, was proposed. In reconsidering this problem, one must analyze the thermodynamics of finite-size corrections to surface tension. In particular, one sees that capillary rise between plates does not measure the interfacial free energy density but, rather, a derivative of the interfacial free energy with respect to a system dimension. The quantity needed to draw definite conclusions, the finite-size residual free energy, can be calculated within the harmonic or Gaussian capillary wave model in d spatial dimensions with the aid of Poisson summation techniques and should yield the correct leading asymptotic behavior. For d=3 and experimentally relevant parameter values, the results are independent of the short-wavelength cutoff needed in the model and can be checked against the theory of conformai covariance at two-dimensional critical points. It is found that the finite-size effects in capillary-rise measurements of surface tension vary as 1/D ² (with a universal coefficient) but are too small to be seen in current experiments.Invited paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

State of the art: interface shear resistance of asphalt surface layers

Interface shear resistance is a measure of the bonding between two layers under shear loading. Adequate interface shear resistance and long-term bonding of the surface to the underlying pavement are critical to the performance of pavement structures. Interface shear strength is a function of adhesion, friction and aggregate embedment or interlock and is commonly modelled as a Mohr–Coulomb type envelope. Measurement of interface shear resistance can be performed in the field on full-scale pavements, in the laboratory on cores recovered from the surface or in the laboratory using samples prepared in the laboratory. However, laboratory testing of cores recovered from the field is likely to be more reliable and repeatable than field testing. There is a large range of test methods and procedures for the measurement of interface bond. These test methods are generally grouped into three main loading mechanisms; axial tension, torsional shear and direct shear. Direct shear tests offer a more comprehensive assessment of the full interface strength. The interface’s resistance to shear can be characterised by its strength, modulus/stiffness or work/energy. The results are affected by the test protocol, tack coat type and application rate, test temperature, applied normal stress and rate of loading, interface condition and post-construction trafficking. Of these, the test temperature is the most influential factor. A number of studies have reported contradictory and conflicting conclusions with regard to the importance of various factors and conditions on the different measures of interface shear resistance. Such inconsistent findings likely stem from the complicated interaction between the various interface conditions and testing protocols. The fundamental factors affecting monotonic interface strength are now reasonably well understood. The focus of future research is expected to be on shear fatigue performance of interfaces.     

Study of Marangoni instability of an evaporating liquid layer

Abstract

The onset of Marangoni instability of an evaporating liquid layer is studied theoretically. By assuming the surface regression of the liquid layer is negligibly small and the surrounding gas phase is asymptotically steady, similarity solutions are obtained prior to the onset of instability. Linear stability analysis is then applied to obtain the critical Marangoni number for the onset of instability. The results indicate that : (1) The onset condition is a strong function of the initial temperature of the liquid layer with which the critical Marangoni number decreases. (2) As time proceeds, the thermal boundary layer thickness near the free surface becomes larger, and the liquid layer becomes more unstable. (3) For a liquid layer with a higher initial temperature (closer to the boiling point) the most unstable mode of the disturbance shifts from a lower wave number to a higher wave number.     

Equation of state for compressed liquids from surface tension

A method for predicting an analytical equation of state for liquids from the surface tension and the liquid density at the freezing temperature ( ₁, ₁) as scaling constants is presented. The reference temperature. T_ref. is introduced and the product (T _ref T ₁ ^{1 2} ) is shown to be an advantageous corresponding temperature for the second virial coeflicienls. B₂(T). of spherical and molecular fluids. Thus, B₂(T) follows a promising corresponding states principle and then calculations for(T) andb(T), the two other temperature-dependent constants of the equation of state, are made possible by scaling. As a result, ( ₁, ₁) are sufficient for the determination of thermophysical properties of fluids from the freezing line up to the critical temperature. The present procedure has the advantage that it can also be used in cases whereT _c andP _c are not known or the vapor pressure is too small to allow accurate measurements. We applied the procedure to predict the density of Lennard-Jones liquids over an extensive range of temperatures and pressures. The results for liquids with a wide range of acentric factor values are within 5%.