Assessing the capacity of turbulent flows to conduct geomorphic work

The primary focus of this research is to investigate the potential of a recently proposed criterion for the precise identification of the hydrodynamic conditions responsible for the onset of entrainment of coarse grains. Knowledge of such near critical flow conditions is important for a variety of applications ranging from environmental hydraulics (such as protection of hydraulic structures from scour) to stream ecology, with regard to the assessment of the ecologically and environmentally sound flow conditions for the protection of stream habitat. Recently introduced theoretical concepts as well as probabilistic modeling approaches are presented. At near incipient flow conditions the magnitude of energetic flow events follows a power law distribution, over a wide range of frequencies, similar to many other geophysical phenomena. This implies that highly energetic flow structures, which have a good potential of impinging on an exposed particle and displacing it downstream, occur less frequently for the same low mobility flow conditions. This is in agreement with the intermittent and episodic character of particle entrainment observed from mobile particle flume experiments at low mobility flows. However, small changes in the mean flow or bed shear stresses may result in significant changes in the distribution of these flow structures. Further, analysis of synchronous time series of particle entrainment and local instantaneous flow upstream of it, allows for extraction and characterization of the scales and magnitudes that are relevant to the displacement of individual particles. In addition to having a sound theoretical basis, the stochastic modeling approach is shown to perform well in defining the condition of incipient motion and more generally the various levels of probability for particle entrainment. 
Bio : Dr. Manousos Valyrakis is a Lecturer in Water Engineering, within the School of Engineering at the University of Glasgow. Before joining the University of Glasgow, he worked at Virginia Tech and VCCER as a Research Associate, where he further researched the environmental impacts and associated risks from the resource extraction industries. He gained a PhD in Environmental Hydraulics from the Department of Civil Engineering at Virginia Tech, funded by NSF, in 2011. He has a Diploma (5 year degree) in Civil Engineering, with distinctions and an MSc (Civil and Environmental Engineering), from Aristotle University of Thessaloniki. 
 
Dr. Valyrakis has about 15 years of experience in environmental hydraulics and experimental/computational fluid mechanics. He is the recipient of several awards and has served as session chair on several international conferences. He has also served as a reviewer and member of the editorial board for a book and many international journals and conferences. He has been invited to present his research on several venues and he has authored or co-authored more than 40 outputs, including many peer reviewed journal papers and 2 invited book chapters.
 
He is the manager of the Water Engineering Laboratory (Rankine Building) where he is currently leading research activities relevant to experimental flow dynamics and eco-hydraulics.