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Title: Behaviour of an axi-symmetric jet in the rotating reference frame
Author: Atthanayake, Iresha
ISNI:       0000 0004 7431 7326
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2018
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Experimental results from comprehensive PIV measurements investigating the dynamics of turbulent jets in a rotating fluid are presented. It is observed that background system rotation induces a time-periodic formation-breakdown cycle of the jets. The flow dynamics associated with this process are studied in detail. It is found that the frequency of the cycle increases linearly with the background rotation rate. The data show that the onset of the breakdown phase and of the reformation phase of the cycle can be characterized in terms of a local Rossby number employing an internal velocity and length scale of the jet. The critical values for this local Rossby number, for onset of breakdown and reformation, scale linearly with a global Rossby number based on the flow conditions at the source. The analysis of the experimental data in terms of relevant stability criteria suggests that the formation-breakdown cycle is due to centrifugal instability and that the temporally fluctuating axial flow plays a prominent role in the process. The development of a turbulent plume subject to background rotation was also briefly investigated by means of PIV, in order to compare its behaviour with the jets. It was revealed that unlike the jets, the plume precesses around the axis of rotation of the background. It was also observed that the mean precession frequency of the plume increases linearly with the rate of background rotation.
Supervisor: Not available Sponsor: University Grants Commission, Sri Lanka ; Open University of Sri Lanka ; Funds For Women Graduates
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QA Mathematics ; TA Engineering (General). Civil engineering (General)