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Title: Kinematic simulation of a turbulent channel flow
Author: Clark, N. R.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2009
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Kinematic simulation is a Lagrangian model of turbulence based on an underlying random Eulerian field. We detail a new method of generating kinematic simulation fields in a channel. We employ a new decomposition for kinematic simulation which ensures that the boundary conditions are automatically satisfied while preserving incompressibility. We impose statistics up to second order, including the Reynolds shear-stress and one-dimensional spectral densities. These fields are used as a Lagrangian model and the statistics of one particle, and particle pairs are calculated in a kinematic simulation of a fully developed stationary channel flow with a Reynolds number based on wall units, of 200. A dimensional analysis of the relative accelerations of particle pairs in the channel is presented. We argue that, in kinematic simulation, the relative acceleration correlation should be approximately stationary and that the variance should increase quadratically in time, for times much smaller than the Lagrangian integral time scales. This is used in an analysis of the second order moments of pair separation, and reltive velocity and compared to the simulation data. Finally we examine the flow structures present in the kinematic simulation fields, concentrating on the log region streak structures, and consider their effects upon the Lagrangian statistics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available