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Title: Measurements of the properties of particle segregation in turbulent flows
Author: Meneguz, Elena
ISNI:       0000 0004 2742 9392
Awarding Body: University of Newcastle Upon Tyne
Current Institution: University of Newcastle upon Tyne
Date of Award: 2011
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This PhD thesis is devoted to the study of the motion of particles/droplets in turbulent flows with relevance to many industrial and environmental applica- tions. A mathematical model has been built to quantify the clustering or prefer- ential concentration of inertial particles into regions of strain and to gain an insight into the mechanism behind such an inertial process in incompressible turbulent flows. The model uses a powerful technique which is referred to here as the Full Lagrangian Method (FLM). This technique is based upon the calcu- lation of the fractional size of an elemental volume of the particle phase along the trajectory of one single particle from which a second order deformation ten- sor or 'Jacobian' is evaluated: Jij = 8Xi(XO, t)/8xO,j with Xo being the particle position at time t = O. By definition, the instantaneous particle concentration is n(t) = n(O)/IJ(t)1 where J(t) = det(Jij) (Osiptsov 2000). In particular, the study quantifies the maximum amount of preferential con- centration of inertial particles via calculation of the compressibility of the parti- cle suspension and its statistical properties. By exploiting the FLM, it has been possible to identify the existence of singularities in the particle concentration field which would be impossible to detect by conventional box counting tech- niques due to spatial resolution limits. The statistical distribution of these sin- gularities and their frequency is evaluated and clearly has an impact on droplet coalescence and the onset of rain. Lastly, this study is able to capture and estimate the role played by the Random Uncorrelated Motion (RUM) at zero separation and to investigate its relation to the onset of singularities: both effects together with preferential concentration are ultimately responsible for particle collisions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available