Secondary currents in open-channel flows such as rivers and canals play a key role in transport of momentum, sediments, nutrients, and other substances. Thus, the knowledge of the secondary currents formation, topology and locations in a cross-section is required for making predictions and assessments relevant to water management and maintenance of water ecosystems. A particular measure of open-channel performance is hydraulic resistance factor and this project therefore will explore how this measure is determined by the secondary currents.
Although the great significance of secondary flows for river processes has long been recognised, their origin, mechanics, effects, and interrelations with the primary mean flow and turbulence are still under debate and continue attracting close attention of hydrologists, geomorphologists, engineers, and, recently, stream ecologists.
The objectives of this PhD therefore are: (1) to advance the theoretical framework for studying secondary flows in straight channels, (2) to clarify interrelations between large-scale turbulence and secondary flows, and (3) to identify secondary flow effects on hydraulic resistance, using rigorous friction factor decomposition into specific contributions from turbulence, secondary currents, and bed roughness.
The key project methodology is experimental, involving experiments in a large flume and advanced Particle Image Velocimetry. The data analyses will involve a wide range of statistical methods such as spectral analysis as well as time-averaged and double-averaged Navier-Stokes equations and decomposition of the friction factor in its components due to turbulence (VLSMs), secondary currents, bed roughness and flow heterogeneity.
The successful candidate should have (or expect to achieve) a minimum of a UK Honours degree at 2.1 or above (or equivalent) in Mechanical Engineering or Civil Engineering or Aerospace Engineering.
Essential background: Physics, Mathematics, Programming, Fluid Mechanics.
Knowledge of: Engineering Mathematics, Fluid Mechanics (with focus on turbulence), Hydraulics, Statistical methods, Programming, Water engineering, Numerical methods.
Formal applications can be completed online: http://www.abdn.ac.uk/postgraduate/apply
. You should apply for Degree of Doctor of Philosophy in Engineering, to ensure that your application is passed to the correct person for processing.
NOTE CLEARLY THE NAME OF THE SUPERVISOR AND EXACT PROJECT TITLE YOU WISH TO BE CONSIDERED FOR ON THE APPLICATION FORM.
Informal inquiries can be made to Professor V Nikora ([email protected]
) with a copy of your curriculum vitae and cover letter. All general enquiries should be directed to the Postgraduate Research School ([email protected]
Nikora, V., & Roy, A.G. Secondary flows in rivers: theoretical framework, recent advances, and current challenges. In Gravel Bed Rivers: Processes, Tools, Environments, edited by M. Church, P.M. Biron, and A.G. Roy, London, Wiley and Sons, 2012, 3-22.
Cameron, S.M., Nikora, V., Stewart, M.T. Very-large-scale motions in rough-bed open-channel flow. Journal of Fluid Mechanics, 2017, 814, 416-429.