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Title: Production mechanisms of intense events
Author: Ferguson, Andrew Neil
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2012
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The Restricted Euler equations, taken from the Vieillefosse model for the velocity gradient tensor, are re-investigated using data from direct numerical simulations of an intense event, rather than using data from forced simulations of homogeneous, isotropic turbulence. The goal is to develop ideas for extensions to turbulence models based on the RE equations that can handle these intense events. With this goal in mind, the new numerical data is compared against the evolution of the RE equations towards a finite time limit and its predictions on how ratios of the RE moments converge. The analysis starts by looking at distributions of the invariants in the R-Q phase space. From this, the analysis then compares the Vieillefosse equations to the full equations and notes that there is a significant change in behaviour around t = 0:5. It is suggested that this is associated with a change in ow topology due to the reconnection of vortex tubes in the flow field. To build a higher-order model, more terms from the full RE equations should be used, which is investigated by looking at the co-evolution of the second invariant Q and the third-order moments, Rw and Rs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QA Mathematics