Resources particle theory

An activity which illustrates this general point in relation to particle theory (the topic of Chapter 2) is included in a publication available from SEP (the Science Enhancement Programme, details of which are given in the Other resources section at the end of this introduction). The first of two group-work tasks in this activity Judging models in science asks students to consider two types of particle models - particles like tiny hard billiard balls particles as molecules with soft electron clouds - and to consider which model better explains a range of evidence based on the observable properties of matter. Students will find that each model is useful for explaining some phenomena, but neither fits all the evidence - and of course both models are stiU found useful in science. 

It must be noted here that most industrial fluidized bed reactors operate in a turbulent flow regime. Trajectory simulations of individual particles in a turbulent field may become quite complicated and time consuming. Details of models used to account for the influence of turbulence on particle trajectories are discussed in Chapter 4. These complications and constraints on available computational resources may restrict the number of particles considered in DPM simulations. Eulerian-Eulerian approaches based on the kinetic theory of granular flows may be more suitable to model such cases. Application of this approach to simulations of fluidized beds is discussed below. 

The basic theory for the study of the scattering of light by aerosols was presented by Mie (1908). This theory generally assumes an ensemble of identical spherical particles and requires considerable computing resources for its solution. Modifications to allow for cylindrical and ellipsoidal particles have also been developed. In practice, simplified formulas are often used (see, e.g., Van de Hulst, 1957). The total extinction coefficient at a particular wavelength can be determined by integration over all particle radii r... 

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