Aspect factor

Recognizing that the ratio Aim in equation (7.26) is the specific surface area and calling 2 IJlf the aspect factor /, which is determined by the particle s geometry, equation (7.26) can be written as... 

The aspect factor,/, equal to 2 IJlf arises from the size and shape of the cross-sectional areas that make up the channels. Therefore,/, is highly dependent upon the particle size and shape. Carman S studied numerous materials and found a value of 5 was suitable in most cases. Various theoretical and experimental values for / usually are found to be in the range 3 to 6. 

Other important geometric channel parameters are the aspect ratio as well as the aspect factor, defined, respectively, as (see Fig. Ic)... 

For noncircular conduits the channel aspect ratio or aspect factor (see Eqs. 2 and 3) has a profound influence on the friction factor Cf = /Re = ApD / piuL, which has a constant value of 16 for circular conduits. For example. Fig. 2c provides a comparison of the simulation results with an empirical correlation of Wu and Cheng [12], i.e.,... 

The flow relationships are concerned with two or more units or items. For example, the flow between two units may involve air, water, steam, lubricating oil, fuel, or electrical energy. In addition, the flow could be unconfined, such as heat radiation from one body (unit) to another body (unit). Problems associated with many products are the proper flow of energy or fluids from one item or unit to another item or unit trough confined spaces or passages, consequently leading to safety-related problems. The flow-related problem causes include faulty connections between units and complete or partial interconnection failure. In the case of fluid, from the safety aspect factors such as those listed below must be considered carefully ... 

PRELIMINARY CONSIDERATIONS SURFACE PROPERTIES RELATED TO FRICTION QUALITATIVE DESCRIPTION OF THE MECHANISM FUNDAMENTAL ASPECTS FACTORS AFFECTING FRICTION RELATIVE MOTION AND TEMPERATURE DISPLACEMENT DEPENDENCE IN INITIAL FRICTION NORMAL LOAD, NOMINAL AREA, PRESSURE AND SURFACE ROUGHNESS MATERIALS FOR FRICTION PAIR Elastomer Properties Counterfaces of Hard Solids EVALUATION OF THEORETICAL MODELS A QUASI-QUANTITATIVE THEORY Friction of Asperities Details of Calculations Other Factors DEFORMATION FRICTION CONCLUSIONS... 

If it is assumed that the aspect factor (k) varies with porosity, it can be determined as a function of porosity using a previously measured value of S. Equation (1.10) may be written ... 

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