Bulk Flow Properties

A tracer is a minute amount of matter similar to the bulk material which is added to a flow system without affecting the bulk flow and the concentration of which is measurable. Obtaining information of the tracer flow by measurements provides information about bulk flow properties. 

A microscopic description characterizes the structure of the pores. The objective of a pore-structure analysis is to provide a description that relates to the macroscopic or bulk flow properties. The major bulk properties that need to be correlated with pore description or characterization are the four basic parameters porosity, permeability, tortuosity and connectivity. In studying different samples of the same medium, it becomes apparent that the number of pore sizes, shapes, orientations and interconnections are enormous. Due to this complexity, pore-structure description is most often a statistical distribution of apparent pore sizes. This distribution is apparent because to convert measurements to pore sizes one must resort to models that provide average or model pore sizes. A common approach to defining a characteristic pore size distribution is to model the porous medium as a bundle of straight cylindrical or rectangular capillaries (refer to Figure 2). The diameters of the model capillaries are defined on the basis of a convenient distribution function. 

The nature of the polymerization reactor also depends upon the desired form of the product (pellet, powder, bead, etc.). For example, extruder reactors (Stuber and Tirrell, 1985) are best suited to producing pellets, sheets, and coatings. The beads that may be directly useful in processing are best produced by the suspension polymerization process. The round beads, however, may not have suitable bulk-flow properties and are dangerous if spilled. Alternate shapes and the appropriate methods of production are, therefore, often employed. 

Tablet diluent Inert substance used as filler to create desired bulk, flow properties, and compression characteristics in preparation of tablets Dibasic calcium phosphate, kaolin, lactose, mannitol, microcrystalline cellulose, powdered cellulose, precipitated calcim carbonate, sorbitol, starch...

All these problems are the result of the interaction of solids, solids flow properties, and the design of the equipment. Johanson (2002) has identified seven indices that relate to the bulk flow properties of solids. 

The most common factors that influence bulk flow properties are ... 

As with bulk density, permeability is a function ofpacking voidage and its uniformity, and in practice, it is best measured. It can vary substantially with previous compaction of the sample. An example is the change in bulk density—and therefore interstitial voidage—that occurs with a material as it moves through a hopper. By applying a load to the upper surface of the bed, permeability may be also determined as a function of solids consolidation pressure (see Bulk Flow Properties ). Permeability is a decreasing function of applied solids pressure, and bulk density is often written in log form, or... 

The objectives of a drilling hydraulics programme are to ensure good hole cleaning, to minimize frictional losses in the flow in the drill pipe and annulus and to minimize the erosion of open hole formations by the shear stress exerted on the borehole wall. Several texts have described drilling fluid (or non-Newtonian fluid) hydraulics in some detail (82-85). The bulk flow properties of the drilling fluid are calculated from the models r = f(y) used to fit the experimental rheological data. 

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