Capillary forces definition

Facilitated transport has been briefly described in Chapter 1. In facilitated transport, the selective transport medium is a liquid or molten salt contained or immobilized in a porous support. The liquid membrane is held tightly in the support pores by capillary forces. The liquid or molten salt selectively reacts with a gas or vapor species and the reacting species diffuses across the liquid or salt and desorbed on the other side of the facilitated transport membrane. The major advantage of the facilitated transpoa is that diffusion is generally several orders of magnitude faster than diffusion through solid membranes. The support is, therefore, not a membrane by definition. Comprehensive... 

Capillary Number in Oil Mobilization. The capillary number is a dimensionless ratio of viscous to capillary forces it provides a measure of how strongly trapped residual oil is within a given porous medium (5). Various definitions have been used for capillary number, but the following equation is common ... 

These definitions recur In the treatment of capillary phenomena, a term that we shall use generally for all features of spatially curved interfaces. For the definition of curvatures and their mathematical treatment, see sec. 1.2. Forces resulting from 11.1.2) are called capillary forces. Anticipating later sections, it is noted that for curved interfaces at equilibrium and in the absence of gravity, Ap is the same everywhere, hence so is the first curvature. In the presence of gravity, this is no longer the case. 

Thomas (2008) defined EOR as a process to reduce oil saturation below the residual oil saturation (Sor). Recovery of oils retained due to capillary forces (after waterflooding in light oil reservoirs) and oils that are iimnobile or nearly immobile due to high viscosity (heavy oils and tar sands) can be achieved only by lowering the oil saturation below Sor. Such a case needs a definition of residual oil saturation different from the conventional one. 

Figure 4.9 Capillary force calculation between two contacting spherical particles having identical radius of Rs. If a liquid completely wets the surfaces of the particles (9 = 0°), then the liquid will condense into the gap around the contact zone, (—r) is the first radius of curvature, and the second radius of curvature is R2 = z by definition, where the distance, z, is as shown in the figure.

Bridging effects. A definite interaction is involved in this process that may include mutual diffusion or "alloying" between the substance of the particle and the surface. Liquid/solid bridging may be involved at the interface that invokes capillary forces. 

The heat pipe is a device that utilizes evaporation heat transfer in the evaporator and condensation heat transfer in the condenser in which the vapor flow from the evaporator to the condenser is caused by the vapor pressure difference, and the liquid flow from the cmidenser to the evaporator is produced by capillary force, gravitational force, electrostatic force, or other forces directly acting on it. A micro heat pipe is so small that the mean curvature of the liquid-vapor interface is comparable in magnitude to the reciprocal of the hydraulic radius of the total flow channel. Mathematically, the definition of micro heat pipe can be expressed as... 

L2 Mechanical Definition Surface Energy and Capillary Force... 

Capillary Forces Laplace Equation (Liquid Curvature AND Pressure) (Mechanical Definition)... 

By definition, a spontaneous capillary flow (SCF) occurs when a liquid volume is moved spontaneously by the effect of capillary forces—without the help of auxiliary devices such as pumps or syringes. Capillary systems can be either confined or open, i.e. the Uquid moves inside a closed channel or in a channel partially open to the air. On the other hand, composite channels—sometimes partly open or with apertures—are increasingly used, and spontaneous capillary flow is a convenient method to move liquids in such geometries. Some examples of SCF are shown in Figure 1.1. 

By definition, any interaction between objects that tends to hold them together is a bond. In our work, capillary interactions provide the bond between objects. In general, a bond between two molecules or objects has two components one attractive, and one repulsive (Fig. 4.3). At some distance, these forces are equal... 

The viscosity of polymer solutions is usually determined by measuring the flow time of a definite quantity of solution through a capillary. The driving force is the height of the fluid in the viscometer. A difficulty arises because polymer solutions are sufficiently oriented in ordinary capillary viscometers so that even at a low rate of shear the viscosity determined does not correspond to its real value at zero shear. In order to get values which are reproducible, regardless of the viscometer used, the viscosities, therefore, have to be determined at several rates of shear and extrapolated to zero shear rate as well as to zero concentration. This is particularly import t for high molecular-weight polymers where the shear dependence of viscosity is most pronounced. 

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