High resolution numerical and experimental studies of turbulence-induced sediment erosion and near-bed transport

Lead Research Organisation: University of Aberdeen
Department Name: Engineering

Abstract

Analysis of turbulence-induced sediment erosion and near-bed transport is vital to many aspects of hydraulic engineering including the design of stable channels, protection of bridge piers, and the development and management of aquatic habitats, to mention a few. Most currently available relationships for predicting sediment erosion thresholds and bed-load transport rates are empirical and employ time- and space-averaged bulk quantities. The predictive power of these formulae is therefore low and errors may well exceed 100 %, which is a reflection of the lack of sound understanding of the physical mechanisms involved. The proposed study will address this knowledge gap using state-of-the-art physical experiments and numerical simulations of flows over spherical and naturally shaped roughness elements. Key research targets include identification and quantification of relationships between instantaneous flow fields (including the region below roughness tops) and resulting forces on sediment particles, assessment of individual bed-load particle trajectories and the interaction of turbulent flow and a multitude of mobile sediment particles. Among others, the effect of Reynolds number, flow submergence, sediment shape, and sediment packing on turbulence structure and near-bed transport will be addressed. The study will be based, for the first time, on the systematic use of highly-resolved numerical simulations with fully resolved mobile roughness elements coupled with advanced three-dimensional experimental measurements above and below mobile sediment beds. The project will bring together three research groups from two countries which complement each other with unique capabilities in addressing a common research goal.

Publications

10 25 50
 
Description 1. New high-resolution data sets on turbulence structure of rough-bed open channel flows have been obtained for a wide range of hydraulic conditions and a refined conceptual model proposed.
2. New high-resolution data sets on drag forces on bed particles in rough-bed open channel flows have been obtained for a wide range of hydraulic conditions and the correlation of drag forces with turbulent eddies have been demonstrated.
3. New high-resolution data sets on particle entrainment in rough-bed open channel flows have been obtained for a wide range of hydraulic conditions and a refined conceptual model of particle entrainment has been proposed.
4. A strong relationship between particle entrainment and turbulent structures has been established and quantified, and the driving entrainment mechanisms identified.
Exploitation Route The project outcomes underpin next generation of the tools for numerical simulation of sediment erosion.
Sectors Energy,Environment,Other

 
Description Aquaculture
Geographic Reach National 
Policy Influence Type Membership of a guideline committee
 
Title Advanced PIV 
Description An advanced Particle Image Velocimetry system and associated algorithms have been developed that allows to make accurate measurements of flow fields in a water tank in a variety of modes and in combination with other instrumentation (see Dr Stuart Cameron's paper in Publications). 
Type Of Material Improvements to research infrastructure 
Year Produced 2013 
Provided To Others? Yes  
Impact The developed advanced PIV system has been used in the field (small rivers), for the first time, by a group of researchers studying flow vegetation interactions in small rivers. 
 
Title Pressure forces on sediment particles in turbulent open-channel flow 
Description This data set is an accompaniment to the journal paper: Mohammad Amir, Vladimir I. Nikora and Mark T. Stewart (2014). Pressure forces on sediment particles in turbulent open-channel flow: a laboratory study. Journal of Fluid Mechanics, 757, pp 458-497 doi:10.1017/jfm.2014.498 The data contained in this record can be used to replicate Figures 8 to 26 in the journal paper. The dataset is organised according to the figure numbers, with each figure having its own sub-folder. Within each sub-folder, there is a Matlab script file (extension .m) which has instructions for plotting the data to recreate the desired figure. The data needed to make the plots is contained in the .mat files within each sub-folder. These .mat files, once loaded in Matlab, can be easily manipulated or exported for analysis in other software. 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? No  
Impact [..] 
URL http://pure.abdn.ac.uk:8080/portal/en/datasets/pressure-forces-on-sediment-particles-in-turbulent-op...
 
Description Dresden 
Organisation Technical University of Dresden
Country Germany 
Sector Academic/University 
PI Contribution Our group shared our experimental data on fixed and mobile bed granular flows to support physical interpretation of numerical simulations conducted by Professor Jochen Fröhlich and his group.
Collaborator Contribution Professor Jochen Fröhlich and his group provided Direct Numerical Simulation (DNS) data on mobile bed flows to compliment our laboratory experiments and their interpretation.
Impact 1. 3 conference papers (see Publications) 2. Two journal papers are under consideration in Journal of Hydraulic Research 3. One keynote talk is invited (TURBINTERMARS 2014 - Turbulence and interactions in Marine Systems. 2014 Special topic: Turbulence and sedimenatery processes)
Start Year 2010
 
Description Karlsruhe 
Organisation Karlsruhe Institute of Technology
Country Germany 
Sector Academic/University 
PI Contribution Our group shared our experimental data on fixed and mobile bed granular flows to support physical interpretation of numerical simulations conducted by Professor Markus Uhlmann and his group.
Collaborator Contribution Professor Markus Uhlmann and his group provided Direct Numerical Simulation (DNS) data on mobile bed flows to compliment our laboratory experiments and their interpretation.
Impact 1. Two research papers are under preparation. 2. One joint keynote is invited (TURBINTERMARS 2014 - Turbulence and interactions in Marine Systems. 2014 Special topic: Turbulence and sedimenatery processes).
Start Year 2010
 
Description Milano 
Organisation Polytechnic University of Milan
Country Italy 
Sector Academic/University 
PI Contribution Theoretical developments and physical interpretations based on extensive laboratory experiments made by the group of Professor Francesco Ballio. Hosting research visits from Milano group to complement research activities.
Collaborator Contribution Professor Francesco Ballio and his group provided unique data sets for joint analysis and interpretation in relation to mobile bed particle motion.
Impact 1. Six journal papers (see Publications) 2. Multiple conference presentations.
Start Year 2008
 
Description Warsaw 
Organisation Polish Academy of Sciences
Country Poland 
Sector Public 
PI Contribution Our group provides our experimental data and supported theoretical developments and physical interpretation of numerical simulations of mobile-bed flows conducted at the Polish Academy of Science by Professor Pawel Rowinski and Dr Robert Bialik.
Collaborator Contribution The Polish Academy of Science group of Professor Pawel Rowinski and Dr Robert Bialik provided their numerical simulation data to support our work on turbulent flows over fixed and mobile gravel beds.
Impact 1. Seven journal papers (see Publications) 2. Multiple conference presentations
 
Description Public lectures 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact The talks have focused on career development of emerging researchers and its enhancement through research publications in specialized peer-reviewed journals

I received feedback from a number of early stage researchers that after my talks their publication style has sharply improved.
Year(s) Of Engagement Activity 2011,2012,2013,2014,2015