Viscosity Of Pure Water Research Articles

Study of variation of optical and physical properties of saline water solutions with temperature

Measurements of refractive index, ultrasonic velocity, density and viscosity of pure water, aqueous NaCl solutions of various concentrations, and sea water collected from Diu sea shore (Gujarat, India), were carried out at temperatures of 20°, 30° and 40 °C. To determine the ultrasonic velocity, density and viscosity; the ultrasonic interferometer, pycnometer and Oswald’s viscometer were used, respectively. For the measurement of refractive index of these solutions at various wavelengths, the LEDs (Light Emitting Diodes) emitting radiations of different wavelength were used along with the Abbes refractometer. Experimental values of refractive indices have been compared with the values calculated using an empirical equation given by McNeil (1977) and Matthus (1974) and are in good agreement with the literature values. Experimental values of ultrasonic velocity of different solutions agree very well with the values calculated using the empirical equation given by Medwin (1975). Acoustical parameters like acoustic impedance (Z), adiabatic compressibility (βa) and intermolecular free length (Lf), were obtained by using values of ultrasonic velocity and density.

Viscosity Measurements of Dialkyl Adipates in the Temperature Range of (283 to 363) K and up to 40 MPa

Viscosity is one of the most important properties for many scientific and technological applications, and therefore it has been the subject of an enormous effort of measurement, correlation, and interpretation. Reliable reference data can be of great help to improve viscosity accuracy, while for viscosity, the only accepted standard is the viscosity of pure water at 20 °C (the reference value recommended by ISO is 1.0016 mPa·s). With the technology and industry advancing, there is a new requirement for reference materials of viscosity covering wide temperature, pressure, and viscosity ranges in order to face the challenge that the order of magnitude of viscosity turns to 1014. Considering the dissatisfaction of the only standard, we put forward these candidates to meet the need of appropriate viscosity standard materials: dimethyl adipate (DMA), diethyl adipate (DEA), dipropyl adipate (DPA), and dibutyl adipate (DBA). These materials have the characteristics of easy to obtain, high purity, high thermal chemical stability, and especially larger viscosity value. In this work, the viscosity was experimentally measured by the vibrating wire viscometer over the temperature range of (283 to 363) K and at pressures up to 40 MPa. The combined expanded uncertainty of the reported viscosity is about 2 % with a confidence level of 0.95 (k = 2). The empirical Andrade–Tait equation was used to correlate the experimental results.

Individual behavior and pairwise interactions between microswimmers in anisotropic liquid.

A motile bacterium swims by generating flow in its surrounding liquid. Anisotropy of the suspending liquid significantly modifies the swimming dynamics and corresponding flow signatures of an individual bacterium and impacts collective behavior. We study the interactions between swimming bacteria in an anisotropic environment exemplified by lyotropic chromonic liquid crystal. Our analysis reveals a significant localization of the bacteria-induced flow along a line coaxial with the bacterial body, which is due to strong viscosity anisotropy of the liquid crystal. Despite the fact that the average viscosity of the liquid crystal is two to three orders of magnitude higher than the viscosity of pure water, the speed of bacteria in the liquid crystal is of the same order of magnitude as in water. We show that bacteria can transport a cargo (a fluorescent particle) along a predetermined trajectory defined by the direction of molecular orientation of the liquid crystal. We demonstrate that while the hydrodynamic interaction between flagella of two close-by bacteria is negligible, the observed convergence of the swimming speeds as well as flagella waves' phase velocities may occur due to viscoelastic interaction between the bacterial bodies.

A macroscopic model for predicting the relative hydraulic permeability of unsaturated soils

A macroscopic model for predicting the relative hydraulic permeability of unsaturated soils is proposed. In this model, pores in unsaturated soils are considered to be parallel flow tubes. The water flow in the pores is assumed to take place in the water film on the inside wall of the flow tubes. The viscosity of pore water is considered to be different from the viscosity of pure water and variable with the variation of degree of saturation. The values of tortuosity factor and pore shape factor of unsaturated soils are estimated theoretically. The theoretical model is verified using experimental data for 32 different soils. For application in engineering practice, the value of viscosity of pore water in different soils is proposed.

Metrology of Viscosity: Have We Learned Enough?

Viscosity is one of the most important properties for many technological and scientific applications, and therefore it has been the subject of an enormous effort of measurement, correlation, and interpretation. This effort is completely inconsistent with the fact that it is probably the fluid property with less independent reference values that can be used by most of the everyday users as guidance, calibration, or designing tools. The only accepted standard, the viscosity of pure water at 20 °C, is unsatisfactory because the viscosity among different fluids can vary by a factor of 1014. Its application in the current step-up procedures to produce certified reference materials of higher viscosity, although useful for industrial purposes, degrades the desired small uncertainty of these values. An analysis of the metrology status for Newtonian liquids viscosity, including the best available measurement methods, applicable ranges, existing reference data, uncertainties, and traceability of the measurements to the SI, is made. The discussion assumes in general the internationally accepted definitions of uncertainty.

Temperature effects on water absorption by three different porous materials

Abstract Absorption of water by relatively dry soil and by chromatography paper, and desorption of water by clay, were measured at constant temperatures close to 278K, 293K, and 306K. Within experimental error, temperature affected absorption of water by soil and chromatography paper simply according to the temperature dependence of the kinematic viscosity and of the air–liquid surface tension of pure water. Desorption of water by saturated bentonite slurry, where there were no air–water interfaces, scaled simply according to the temperature effects on the kinematic viscosity of pure water.

Peculiar rheological properties of dilute aqueous solutions of polymers in contact with a rotating disc

The anomalous decrease of apparent solution viscosity (measured by a rheoviscometric system with a metal disc) below the viscosity of pure water was monitored by studying highly diluted solutions of water-soluble polymers. The phenomenon suddenly vanishes below 35°C, which is not the case for a simple drag reduction. It is suggested that the explanation is in the complex functioning of drag reduction and viscoelastic behaviour of the adsorbed polymer layer at the metal disc.

The viscosity of dilute aqueous nonelectrolyte solutions

An equation is proposed to describe the viscosity B coefficients for dilute solutions of nonelectrolytes in water. It is based on an empirical equation developed for nonaqueous mixtures and an assumption that the entropy change on solution of the liquid solute affects the viscosity of the aqueous system in the same way as a change of molar entropy affects the viscosity of pure water. The equation is shown to represent experimental results well and is especially successful in representing the temperature dependence of the B coefficient for aqueous solutions of alcohols.

Dielectric relaxation studies of solutions of 1:2, 2:1 and 2:2 electrolytes in water

The complex permittivity of a series of aqueous solutions of 1:2, 2:1 and 2:2 electrolytes has been measured in the frequency range, 0.3 to 37 GHz at 21°C. For solutions of K2SO4, Ni(ClO4)2 and the nickel salt of m-benzene disulphonic acid, the experimental data are adequately described by a single relaxation time characteristic of the solvent. With solutions of NiSO4, CuSO4, hexammine nickel(II) sulphate and bis-ethylene diamine copper(II) sulphate, an additional Debye-type relaxation process characteristics of the salt is observed. From the amplitude of this solute dispersion, the dipole moments of the ion pairs, assumed to be responsible for it, have been calculated. Centre-to-centre distances estimated from these electric moments are all of the order of 0.4 nm and are also consistent with the values of the experimental relaxation times for the solute dispersion, provided that the ion pairs can be regarded as prolate ellipsoids, which relax by rotational diffusion at a rate which is inversely proportional to the macroscopic viscosity of pure water.

The Viscosity of Water under Pressure

Abstract : The effect of hydrostatic pressure on the viscosity of pure water has been measured with a rolling-ball type of viscometer over the pressure and temperature ranges of 1 to 2,000 kg/sq cm and 2 to 20 C. The application of pressure tends to destroy the structured regions in liquid water. (Author)

The Activation Energy of Viscous Flow of Pure Water and Sea Water in the Temperature Region of Maximum Density

Abstract : The viscosity of pure water and sea water have been measured at one atmosphere over the temperature range -2 to +12C. The temperature-dependence of the activation energy of viscous flow of water and aqueous electrolytic solutions, unlike that of the activation energy of the electrical conductivity of aqueous solutions of salts, does not exhibit a maximum near the temperature of maximum density. This dissimilarity casts doubt upon the hypothesis that viscous flow and 'normal' electrical conductivity both have the same slow step, namely, 'hole'-formation in the water. (Author)

Notes on the Fluidity of Water in the Vicinity of 20°C

Measurements of viscosity are practically all relative, since viscometers are calibrated with a liquid whose viscosity is assumed to be known, but many different values of the viscosity of water are in use dependent upon the authority consulted, or the conditions of temperature and upon the corrections which are made in the reduction of the data, and quite as often as not the final results are expressed as specific viscosities of one kind or another. Bulletin No. 278 of the U. S. Bureau of Standards contained certain proposals. (1) It was proposed that all viscosities be expressed in absolute units even though the measurements be relative. (2) Since the viscosity of water at 20°C is close to 0.0100 c. g. s. units, it was proposed to adopt the viscosity (or fluidity) of water at this particular temperature for the fundamental rheological standard. (3) By making the one-one hundredth part of the c. g. s. unit the practical unit of viscosity, and calling it the centipoise (cp) an advantage would be gained in that viscosities would all be specific. This would be perhaps most appreciated in studying the viscosity of electrolytic solutions, which are compared with the viscosity of pure water. (4) Different authorities were compared, the later corrections added, and an attempt made to secure the best value to be used as standard. Since the viscosity may be calculated by formula from values in the vicinity of 20°, these values were also not neglected in arriving at the most probable value, which was given as 1.005 cp.