Trajectory effect

These estimated latitudinal distributions are modified somewhat by winds carrying pollutants downwind from the source areas. However, the general west-to-east movement of air masses and the concentration of pollutants into the lower portion of the troposphere tend to minimize wind trajectory effects on the patterns shown in Figures 3 and 4. 

Subscript 1 indicates continuous phase and 2 indicates dispersed phase. Cd is a parameter of the standard k-s model (0.09), k is turbulent kinetic energy and si is turbulent energy dissipation rate. The eddy lifetime seen by dispersed phase particles will in general be different from that for continuous phase fluid particles due to the so-called crossing-trajectory effect (Csnady, 1963). This can be expressed in the form ... 

Figure 4.11 Generation of topographic contrast (a) the trajectory effect, which arises from the orientation of surface with respect to the detector in an SEM, is similar to (b) reflected light effects from the orientation of surface with respect to the light source in a light microscope. (Reproduced with kind permission of Springer Science and Business Media from J.I. Goldstein et al, Scanning Electron Microscopy and X-ray Microanalysis, 2nd ed., Plenum Press, New York. 1992 Springer Science.)...

The crossing trajectory effect refers to the impact of the continuous change of the fluid eddy-particle interactions as the heavy particle trajectory might go through numerous eddies reflecting different flow properties. Hence it follows that the velocity history of heavy particles may differ from that of a marked fluid particle. Similar closure models for the drift velocity and the velocity co-variances have been derived from kinetic theory by Koch and co-workers [38, 39] and Reeks [62, 63]. 

Grehan, G., Gouesbet, G., Nagwi, A. and Durst, F., On elimination of the trajectory effects in phase-Doppler systems. Proc. 5th European Symp. Particle Characterization (PARTEC 92), pp. 309-318 (1992)... 

Although o)cT is almost invariably too small to yield information about the Fermi surface topology, the modifications to the conduction electrons trajectories produce a modest positive magnetoresistance, which apparently dominates at the lowest temperatures (fig. 6.44). A satisfactory separation of the spin-wave scattering and electron trajectory effects has not yet been achieved. 

At energies of a few eV or less, where large trajectory effects arise, a quantal method is to be preferred at higher energies either a semi-classical (impact parameter) or quantal method is satisfactory. 

Extensive reviews of turbulent diffusion were provided by Levich andHinze. Tchen ° was the first investigator who modified the Basset-Boussinesq-Oseen (BBO) equation and applied it to study motions of small particles in a turbulent flow. Corrsin and Lumley pointed out some inconsistencies of Tchen s modifications. Csanady showed that the inertia effect on particle dispersion in the atmosphere is negligible, but the crossing trajectory effect is appreciable. Ahmadi and Ahmadi and Goldschmidt smdied the effect of the Basset term on the particle diffusivity. Maxey and Riley obtained a corrected version of the BBO equation, which includes the Faxen correction for unsteady spatially varying Stokes flows. 

Figure 4-56 Trajectory effect expressed in terms of geometric optics.

Moving fill point. The use of a rotating chute, mechanically driven or responsive to the inertia of the flow stream by changing the direction of flow, will disperse the in-feed. Consideration should be given to minimising trajectory effects on the fill profile. 

---