Resistance viscous

By analogy with Eq. (2.47), we write the force of viscous resistance experienced by a molecule in an array of uniform molecules of degree of polymerization n as... 

The phenomena under discussion are viscoelastic we have only considered the elastic forces. Next we must incorporate viscous forces. As indicated above, we use Eq. (2.47) to express the proportionality between the viscous resistance to displacement and the velocity of the bead, dZj/dt ... 

From Eq. (9.1) we see that the viscous force associated with this motion equals [i7(dv/dr)] (area), where the pertinent area is proportional to the surface of the sphere and varies as. This qualitative argument suggests that the viscous force opposing the relative motion of the liquid and the sphere is propor tional to [t7(v /R)] (R ). The complete solution to this problem reveals that both pressure and shear forces arising from the motion are proportional tc 77Rvj., and the total force of viscous resistance is given by... 

This concludes our discussion of the viscosity of polymer solutions per se, although various aspects of the viscous resistance to particle motion continue to appear in the remainder of the chapter. We began this chapter by discussing the intrinsic viscosity and the friction factor for rigid spheres. Now that we have developed the intrinsic viscosity well beyond that first introduction, we shall do the same (more or less) for the friction factor. We turn to this in the next section, considering the relationship between the friction factor and diffusion. 

A force of viscous resistance is proportional to the stationary-stage velocity Vj according to Stokes law ... 

VG - ami ton. viable - capable of living, viscosity - the resistance of a liquid to flow, resulting from the combined effects of internal friction and friction between the liquid and its surroundings, viscous - resisting flow. 

Bueche (16,152) had earlier proposed a related theory based on a spring-bead model (springs with a rubberlikc elasticity spring constant coupled in a linear chain by beads whose friction factor supplies the viscous resistance). This theory as extended by Fox and co-workers (28,153) gives... 

The velocity times the Stoke s friction factor gives the viscous resistive force ... 

This model makes use of the same concepts as for inviscid liquids except that the viscous resistance is now taken into consideration. Further, the... 

The extra viscous resistance due to expansion to be included in the analysis is... 

In the viscous resistance term in Eq. (163), the radius r can be taken as 1.25 rfb without causing a great loss in accuracy. Equations (162) and (163) reduce to constant flow or constant pressure conditions, respectively, when Q is constant or when it is expressed in terms of orifice equation. 

Inspiration The line ABC is the physiological line traced on inspiration. The area ACDA represents work to overcome elastic tissues resistance. The extra area enclosed by ABCA represents the work done in overcoming viscous resistance and friction on inspiration. If this resistance increases, the curve bows to the right as shown. 

Diagrammatic representation of DNA denaturation. Upon perturbation, the first "melting" away of structure occurs within AT-rich regions, and further perturbation causes this local disorder to grow, such that GC-rich regions are the last to become disordered. The DNA unwinding reaction is limited by viscous resistance. 

Voigt-Kelvin model or element Model consisting of an ideal spring and dashpot in parallel in which the elastic response is retarded by viscous resistance of the fluid in the dashpot. 

In which element or model for a viscoelastic body will the elastic response be retarded by viscous resistance (a) Maxwell or (b) Voigt-Kelvin ... 

If 7 > coo, the characteristic equation Eq. (10.7) has two negative real roots. The viscous resistance is large that the mass creeps to its equilibrium position from any initial condition. 

The left-hand side of the latter equation is related to the liquid inertia, whereas both terms in the right-hand side are related to capillarity (the driving force), and viscous resistance, respectively. Under steady conditions, capillarity is balanced by the viscous drag of the liquid, and the famous Lucas-Washbum s equation can be derived (De Geimes et al., 2002) ... 

Both the fluid mechanics and the statistical mechanics on which some of the key theoretical results of the chapter are based are sufficiently complicated that we only sketch the highlights of these topics. We attempt to impart some physical plausibility to these theories, however, by using both force and energy perspectives in discussing the viscous resistance to flow. 

Since the force under consideration measures viscous resistance to flow, the quantity dE/dVmeasures the energy dissipated per unit volume. 

An ion in an electric field thus experiences an acceleration toward the oppositely charged electrode. However, its velocity does not increase without limit. An opposing force due to the viscous resistance of the medium increases as the particle velocity increases ... 

The situation is thus very much like the sedimentation velocity discussed in Chapter 2 in which the gravitational forces on a particle are opposed by viscous resistance. 

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