Number-averaged particle radius determination

This structure is generated via the modified diffusion-limited aggregation (DLA) algorithm of [205] using the law p = a (m/N). Here, N = 2, 000 (the number of particles of the DLA clusters), a = 10 and ft = 0.5 are constants that determine the shape of the cluster, p is the radius of the circle in which the cluster is embedded, pc = 0.1 is the lower limit of p (always pc < p), and to is the number of particles sticking to the downstream portion of the cluster. This example corresponds to a radial Hele-Shaw cell where water has been injected radially from the central hole. Due to heterogeneity a sample cannot be used to calculate the dissolved amount at any time, i.e., an average value for the percent dissolved amount at any time does not exist. This property is characteristic of fractal objects and processes. 

We can use the same record of the trajectory of a particle to determine at the same time its hydrodynamic radius and its density. For sedimentation at low Reynolds number, the average vertical velocity is given by the balance between the body force and the friction force ... 

The average particle-size distributions for a number of fireclays are shown in Table 14. Particles larger than 2(jl equivalent spherical radius are determined by a method based on settling under gravity, but for smaller particles a centrifugal method has to be employed. It is unfortunate that more information on the distribution below 2(jLis not available, since it is this fraction that contributes most to the specific surface area and related properties. Nevertheless, the data available does correlate to some extent with other physical properties. 

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