Gravitational and Centrifugal Fields

The flow problems considered in Volume 1 are unidirectional, with the fluid flowing along a pipe or channel, and the effect of an obstruction is discussed only in so far as it causes an alteration in the forward velocity of the fluid. In this chapter, the force exerted on a body as a result of the flow of fluid past it is considered and, as the fluid is generally diverted all round it, the resulting three-dimensional flow is more complex. The flow of fluid relative to an infinitely long cylinder, a spherical particle and a non-spherical particle is considered, followed by a discussion of the motion of particles in both gravitational and centrifugal fields. 

In this volume, we will apply the principles developed in Principles and Applications to the description of topics of interest to chemists, such as effects of surfaces and gravitational and centrifugal fields phase equilibria of pure substances (first order and continuous transitions) (vapor + liquid), (liquid 4-liquid), (solid + liquid), and (fluid -f fluid) phase equilibria of mixtures chemical equilibria and properties of both nonelectrolyte and electrolyte mixtures. But do not expect a detailed survey of these topics. This, of course, would require a volume of immense breadth and depth. Instead, representative examples are presented to develop general principles that can then be applied to a wide variety of systems. 

In this chapter the thermal motion of dissolved macromolecules and dispersed colloidal particles will be considered, as will their motion under the influence of gravitational and centrifugal fields. Thermal motion manifests itself on the microscopic scale in the form of Brownian motion, and on the macroscopic scale in the forms of diffusion and osmosis. Gravity (or a centrifugal field) provides the driving force in sedimentation. Among the techniques for determining molecular or particle size and shape are those which involve the measurement of these simple properties. 

In this chapter, we study the effects of uniform static electric and magnetic fields on the thermodynamic properties of material. The source of the fields may be in the surroundings or included in the system of interest. In either case, the properties of the material affect the value of the effective field at any point in the material. It is for this reason that the study of electric and magnetic fields is more complicated than the study of gravitational and centrifugal fields presented in the next chapter. 

In this chapter, we study the effects of gravitational and centrifugal fields on the thermodynamic properties of systems. We generalize many of the results obtained in previous chapters to include the effects of these fields. 

Gravitational and Centrifugal Fields For a system consisting of a pure ideal gas,... 

Voit, H. Zeppenfeld, R. Mersmann, A. Calculation of Primary Bubble Volume in Gravitational and Centrifugal Fields, Chem. Eng. Technol. 10 (1987), p. 99/103... 

The size distribution of supramolecular polymers should be sensitive not only to changes in the solvent conditions, but also to externally applied fields including electric and magnetic fields [82,83], flow fields [84-86], gravitational and centrifugal fields [87,88], confining walls [89,90], and so on. 

This chapter will present the very important kinetic properties of coUoids, and their motion under the influence of gravitational and centrifugal fields. Kinetic properties are important for many reasons, for example they provide methods for determining the molecular weight (molar mass) of colloidal particles, their size and shape - i.e. for the characterization of colloidal particles. Many of the methods we will see in this chapter have found widespread use in the study of biological and polymeric molecules. 

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