Dunstan, Samuel David (2020) DNS of convective rotational turbulence in the pipe, concentric pipe and jet. PhD thesis, University of Warwick.

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Abstract

The spectral element solver nek5000 is used to resolve direct numerical simulation of convective1 rotational turbulence in a pipe and a concentric pipe with inner and outer wall rotation. The turbulent pipe jet is also examined and discussed. Rotation is applied to the pipe jet and the transient effects are examined. An attempt is made to discuss how basic universal laws governing rotation apply in rotational turbulence. Such laws include those governing angular velocity, angular momentum and centripetal acceleration. It is known that the fluctuating velocity components of turbulence are rotationally invariant. By studying the first three classes of rotational turbulence in this research, it is shown that with rotation, the instantaneous flow settles in the rotational reference frame, regardless of the static wall for the concentric pipe classes. The importance of the energy partition parameter, which is the ratio of streamwise velocity fluctuations to the sum of radial and azimuthal velocity fluctuations, towards the formation of eddy elongation is demonstrated. The role of Rossby number in the rotational reference frame, in forming inertial waves is shown. Dominant positive azimuthal vorticity in the wall bounded classes of rotational turbulence studied, are shown to become amplified in the pipe jet. An extrapolation about how this prominent positive azimuthal vorticity reacts under rotation is made. The problem statement of this research has been to gain a better understanding of rotational turbulence and particularly that which is convective. Qualitative imagery and data have been amassed. Quantitative analysis whilst basic is still able to convey novel physics of convective turbulent fluid flow in a rotating reference frame.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QA Mathematics Q Science > QC Physics T Technology > TA Engineering (General). Civil engineering (General)
Library of Congress Subject Headings (LCSH):	Turbulence, Jets -- Fluid dynamics, Pipe -- Fluid dynamics, Rotational motion, Eddy flux, Rossby number
Official Date:	May 2020
Dates:	Date Event May 2020 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Chung, Yongmann M.
Sponsors:	Commonwealth Scholarship Commission in the United Kingdom ; Papua New Guinea University of Technology
Format of File:	pdf
Extent:	xx, 270 leaves : illustrations, charts
Language:	eng

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