Applications are invited to apply for a 4-year PhD studentship in experimental fluid mechanics at the Applied Mathematics Research Centre, Coventry University (http://www.complexity-coventry.org/home/). The project is funded by the National Engineering Laboratory, who provides calibration services for flowmeters used in offshore oil extraction plants (www.tuvnel.com). Precisely measuring the quantity of oil extracted from wells is a major economical challenge for the oil industry. Current flowmeters rely on assumptions on the flow profile in pipelines, which are being challenged both by the multiphase nature of the flow and its transitional character. To measure flow rates more precisely, it is now necessary to characterize flow regimes in real time, and this demands a precise understanding of the transition between laminar and turbulent states in multiphase pipe flows.

Pipe flow is a classical problem in fluid dynamics. Its simplicity of form and importance to industry and engineering has invited research for well over 100 years. In the case of a single phase the problem is relatively well understood in terms of transient turbulence. Patches of turbulence can be observed once the nondimensional flow rate (Reynolds number) exceeds 2000. As the flow rate is increased, turbulence becomes easier to initiate and turbulent patches start to spread along the pipe. With the addition of solid particles to the flow, the picture becomes less clear. Despite the great importance of particulate flow to a range of real world problems from chemical engineering to food processing, our understanding of how solid-liquid multiphase flow behaves is relatively poor. In the case of fully developed turbulence, work has been done on the impact of particle size on turbulence intensity and particle distribution. Somewhat less has been done on the problem of intermittent turbulence, and turbulence transition. These questions need to be answered to be able to determine flow rate precisely from the signals delivered by standard flowmeters.

The doctoral student will be in charge of the numerical part of this work. Transitional particulate channel flow has previously been investigated, but only in the case of the small periodic boxes. That literature will inform the beginnings of this project as we seek to employ similar methods in initially periodic pipe flow before moving to non-periodic flow. Cutting edge ideas (exact solution finding, nonlinear transient growth, etc) from the classical transition problem will be applied to this new field. The work will be compared extensively to experimental work to validate the approach taken and the results will be used to obtain more precise measurements from current and future flowmeters.

This challenging problem offers a rare opportunity for high-profile fundamental research in fluid mechanics (typically expected to generate publications in leading journal such as Journal of Fluid Mechanics) with, at the same time, a direct application to a concrete industrial need.

Successful candidates are expected to hold a MSc or equivalent in fluid mechanics or a related discipline (Physics/ Engineering/ Mathematics) and experience of numerical coding. Abilities in this field will have been demonstrated at MSc level.  The student will receive a tax-free bursary in excess of approx. £13.5k per annum (approx £17kEuros). Please note that this position is available to EU citizens only. The position will be open until a suitable candidate is found.

To apply, please forward a CV and academic records to Chris Pringle (chris.pringle(at)coventry.ac.uk) or Alban Pothérat (alban.potherat(at)coventry.ac.uk). Informal enquiries are welcome. The position will remain open until a suitable candidate is found.

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Alban Potherat
Coventry University
Applied Mathematics Research Centre