Fluid globules

Baygents, J.C. and Saville, D.A., Electrophoresis of small particles and fluid globules in weak electrolytes, J. Colloid Interface Set, 146, 9, 1991. 

Fig. 2 Schematic phase diagram of a single flexible polymer chain in the thermodynamic limit (Af —> Qo) as a function of temperature T and range of attractive monomer-monomer interaction X. For 2 > At, there occurs a transition at T = 6 X) from the swollen coil to the collapsed fluid globule. At TcystCiV = < ) the globule crystalhzes. Due to slow crystallization kinetics, this transition may be undercooled and at FcystW the collapsed globule freezes into a glassy slate. Since it was assumed that the transition lines vary linearly with the interaction volume A, A rather than A has been chosen as an abscissa variable. Adapted from Binder et al. [4]...

When water is injected into a water-wet reservoir, oil is displaced ahead of the injected fluid. Injection water preferentially invades the small- and medium-sized flow channels or pores. As the water front passes, unrecovered oil is left in the form of spherical, uncoimected droplets in the center of pores or globules of oil extending through intercoimected rock pores. In both cases, the oil is completely surrounded by water and is immobile. There is htde oil production after injection water breakthrough at the production well (5). 

In this method a large bulk of one of the fluids is broken into smaller particles inside a continuous phase of the other fluid. This can be caused either by an artificial stirring action or by the instability of the big globule itself. A typical example of this method is the rupture of bubbles during their ascent in a stirred-tank reactor. 

Under these circumstances [said Davy] a vivid action was soon observed to take place. The potash began to fuse at both its points of electrization. There was a violent effervescence at the upper surface at the lower, or negative, surface, there was no liberation of elastic fluid but small globules having a high metallic lustre, and being precisely similar in visible characters to quicksilver, appeared, some of which burnt with explosion and bright flame, as soon as they were formed, and others remained, and were merely tarnished, and finally covered by a white film which formed on their surfaces. 

Samuelsson (1966) concluded, on the basis of his studies, that the close proximity of a copper-protein complex to the phospholipids which are also associated with the fat globule membrane is an important consideration in the development of an oxidized flavor in fluid milks. Haase and Dunkley (1970) stated that although some aspects of catalysis of oxidative reactions in milk by copper still appear anomalous... the mechanism of oxidized flavor development with copper as catalyst involves a specific grouping of lipoprotein-metal complexes in which the spatial orientation is a critical factor. ... 

The increase in viscosity when fluid milk or concentrated milk is heated sufficiently to aggregate the proteins is discussed in Chapter 11. The effects of homogenization and clustering of the fat globules on their contribution to the viscosity of the product are dealt with in Chapter 10. 

Natural convection is the flow induced by the unequal pull of gravity on fluid elements of different densities. For example, if we inject a globule (or layer) of dense aqueous solution marked with a dye into a beaker of water, the dense globule will be observed to sink under the influence of gravity, as illustrated in Figure 4.8. That sinking motion is actually a form of bulk displacement or flow, specifically natural convective flow. 

If fat globules are present as separate particles, the fat content is <40% and the milk fat completely molten, milk and cream behave as Newtonian fluids at intermediate and high shear rates (Phipps, 1969 McCarthy, 2003), i.e., its viscosity is not influenced by shear rate (t = rj / y, where r is the shear stress [Pa], 17 is the viscosity [Pa s] and y is the shear rate[l/s]). For a Newtonian fluid, Eilers equation (Eilers, 1941) is generally obeyed (Walstra, 1995) ... 

At a temperature <40°C, milk does not behave as a Newtonion fluid the deviation from Newtonian flow becomes larger as the temperature decreases (Randhahn, 1973 Wayne and Shoemaker, 1988 Kristensen et ah, 1997). Viscosity of milk decreases with increasing shear rate at a temperature below 40°C (Randhahn, 1973), which Mulder and Walstra (1974) suggested may be due to disruption of clusters of milk fat globules, which were formed as a result of cold agglutination. 

Figure 10.3. Electron micrograph of fluid whipping cream f fat globules.

Boerhaave s emphasis on the smallest particles of matter and the powers peculiar to every part of the body, means that he moved away from the traditional attention to the nature of the blood. Instead of discussing the relatively big globules of the blood he is far more interested in the smallest vessels and fluids of the nervous system. In his Institutiones medicinae he had already pointed to the importance of the nerves in the explanation of motion and also in the process of nutrition. The last process can only take place in the smallest vessels of which the larger vessels are built. This means that the particles of the chyle are too big and unable to nourish and repair the solid parts of the body. For this reason, Boerhaave argued that nutrition chiefly happens in the nerves, with the nervous juice, which is the most subtle humour prepared from the serum of the blood, feeding the solid parts. Boerhaave called this process one of the ultimate and most perfect actions of nature. ... 

Globulation is the formation of droplets of solution, slurry, or melt followed by solidification by prilling, spray drying, or fluid bed techniques. Control of particle size is best achieved in fluidized beds. 

The main assumptions made in arriving at eq 10 were (1) no interaction between the globules and (2) no slippage at the particle-fluid interface. Most emulsions of practical interest exceed the concentration for which eq 10 is valid. With increasing concentration, the hydrodynamic interaction between the globules increases, and eventually mechanical interference occurs between the particles as packed-bed concentrations are approached. To take into account the increased hydrodynamic interaction, many investigators (30, 38-43) have expanded eq 10 into the polynomial form ... 

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