Pressure viscosity

Fig. 10. Viscosity—pressure curve for typical petroleum oils (—) paraffinic (-) aUcycHc and ( ) soHd. To convert MPa to atm, divide by 0.101.

Whilst temperature rises at constant pressure cause a decrease in viscosity, pressure rises at constant temperature cause an increase in viscosity since this causes a decrease in free volume. It is in fact found that within the normal processing temperature range for a polymer it is possible to consider an increase in pressure as equivalent, in its effect on viscosity, to a decrease in temperature. 

The uncertainty of calculating the Poiseuille number from the measurements must be taken into account. The viscosity-pressure relationship of certain liquids (e.g., isopropanol, carbon tetrachloride) must be kept in mind to obtain the revised theoretical flow rate. The effect of evaporation from the collection dish during the mass flow rate measurement must be taken into consideration. The effect of evaporation of collected water into the room air may not be negligible, and due to the extremely low mass flow rates through the micro-channel this effect can become significant. 

The system of equations, including the Reynolds, him thickness, load balance, viscosity-pressure, and viscosity modih-cation equations, is simultaneously solved with the help of a multilevel technique described by Venner and Lubrecht with modihcations to take account of the variation in viscosity. The invariant parameters used in the computation are Z = 0.67, = 226 GPa, o = 0.04 Pa s, p j = 0.46 GPa, R... 

To compare with experimental results, the parameters corresponding to real conditions were used in our computation cases. The lubricant used in the experiment is polyglycol oil. The diameter of the steel ball is 25.4 mm, elastic modulus of the balls is 2.058 X 10 Pa, and the elastic modulus of the glass disk is 5.488 X 10 ° Pa. The circumstance temperature is 28 1 °C. The oil viscosity-pressure index is taken as 1.5 X10- Pa-. ... 

Column gas velocity is dependent upon the column length, carrier gas viscosity, pressure drop through the column and the column permeability. Column permeability is expressed by the specific permeability coefficient, B0, which may be calculated by the following expression. 

Pressure GOR Density Viscosity Pressure GOR Density Viscosity ... 

Third, a serious need exists for a data base containing transport properties of complex fluids, analogous to thermodynamic data for nonideal molecular systems. Most measurements of viscosities, pressure drops, etc. have little value beyond the specific conditions of the experiment because of inadequate characterization at the microscopic level. In fact, for many polydisperse or multicomponent systems sufficient characterization is not presently possible. Hence, the effort probably should begin with model materials, akin to the measurement of viscometric functions [27] and diffusion coefficients [28] for polymers of precisely tailored molecular structure. Then correlations between the transport and thermodynamic properties and key microstructural parameters, e.g., size, shape, concentration, and characteristics of interactions, could be developed through enlightened dimensional analysis or asymptotic solutions. These data would facilitate systematic... 

The rate of foam drainage is determined not only by the hydrodynamic characteristics of the foam (border shape and size, liquid phase viscosity, pressure gradient, mobility of the Iiquid/air interface, etc.) but also by the rate of internal foam (foam films and borders) collapse and the breakdown of the foam column. The decrease in the average foam dispersity (respectively the volume) leads the liberation of excess liquid which delays the establishment of hydrostatic equilibrium. However, liquid drainage causes an increase in the capillary and disjoining pressure, both of which accelerate further bubble coalescence and foam column breakdown. 

This section discusses viscoelastic fluid viscosity, pressure drop during viscoelastic flow, and factors affecting viscoelastic behavior. 

Viscosity-pressure behaviour The relationship between viscosity and pressure, the pressure viscosity coefficient, is an important parameter for lubrication performance. Higher values are obtained for polymers with a high degree of propylene oxide units. 

TABLE I. Viscosity Coefficients and their Isobaric and Isochoric Temperature Coefficients for a Number of CommonLiquids at 30° C. and 1 atm. (The viscosity-pressure coefficient data are from... 

The complex shape of the viscosity-pressure behaviour gives way to simple universal scaling when volume replaces pressure (Fig. 3.53). The physics underlying this scaling can be expressed through the free volume equation. The normalized form of this equation is... 

TABLE 4-3. VISCOSITY-TEMPERATURE AND VISCOSITY-PRESSURE COEFFICIENTS (a)... 

VISCOSITY-PRESSURE-TEMPERATURE BEHAVIOR OF THREE NORMAL PARAFFINS. M.S. THESIS. 

MEASUREMENT AND PREDICTION OF VISCOSITY-PRESSURE CHARACTERISTICS OF LIQUIDS. 

There are as yet no theoretical correlations capable of predicting the viscosity, pressure drop and heat transfer coefficient in the preheater. Some empirical correlations for this purpose are available in the literature (11,13-16,38). The hydro-dynamic characteristics of three phase slurry reactors have been extensively reviewed (1,39,40,41). Suitable correlations have... 

Another topic of recurring interest associated with the simulation of shear flow in atomic liquids is the shear-rate dependence of the viscosity, pressure and other thermodynamic quantities. Marcelli et al. performed homogeneous shear flow NEMD on a fluid interacting with two-body, (p2, and three-body, 3, terms in the interaction potential. The three-body potential term was... 

Thermal conductivity is an important parameter used for material thermal calculations in the injection molding simulation. A variation in the thermal conductivity will alter the cooling rate and hence cause a variation in the temperature this in turn will cause the viscosity, pressure, and frozen layer to vary. Classical Fourier theory, which assumes thermal conductivity to be a constant scalar value depending only on temperature alone, is inadequate to describe the heat conduction in deformed molten polymer. Van den Brule (1989, 1990) and van den Brule and O Brien (1990) suggested that heat transport mechanisms along the backbone of a polymer chain are more efficient than those between neighboring chains. Hence, the orientation of polymer chain segments induced by flow leads to an anisotropic thermal conductivity. To describe anisotropic thermal conduction, one... 

In Eq. [9.6], the fiber bundles are assumed to be completely impregnated instantaneously as the flow front passes through. If one would like to investigate the microvoid formation in the bundles, usually a sink term is added to Eq. [9.6]. " In that approach, the microvoid dimensions and strength of the sink are related to the viscosity, pressures of the void-free surface and capillary, and the permeability of the fiber bundle. 

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