KADWCI -
Kinematics and Dynamics of Waves/Current Interactions
Contents of this page:
- Project objectives
- UCL's role
- KADWCI personnel at UCL
- Duration of project
- Partners
The KADWCI project unites teams from seven research institutions across Europe: University College Cork (UCC), University College London (UCL), Delft Hydraulics (DH), Norwegian Institute of Technology (NTH), UST Lille (USTL), Imperial College London (ICL), and the Technical University of Delft (DUT). UCC acts as Co-ordinator, and the Technical Committee is comprised of members from the first three named institutions.
The primary objective is to study Wave-Current Interactions from a complete fundamental process viewpoint. Sediment is not being included and attention is primarily restricted to a rigid horizontal bed, but with both regular and irregular waves in two and three dimensions.
The project concentrates upon both the kinematics of the whole flow field and bed shear stresses: both are being measured simultaneously in the experimental programme wherever possible. The acquisition of reliable field data to understand shear stresses forms an integral part of this project. All data are being used for input to numerical models, validation of existing models, and assessment of real fluid effects.
The development of predictive numerical models is accompanying the experimental programme and is specifically targeted at those areas for which the theories are not yet well developed. These include wave kinematics in 3-d (regular and irregular) and the prediction of kinematics and bed shear stresses simultaneously using complete flow models. Experiments at all scales are serving an illuminatory role, rather than just for model validation. Without such a role, consistent models for complicated natural phenomena cannot be developed.
As a Contractor and member of the Technical Committee, the UCL Civil Engineering department provides the dominant experimental expertise in the project. Experiments are being performed using UCL's own facilities and at the UK Coastal Research Facility at HR Wallingford. UCL possesses considerable expertise in the measurement of bed shear stresses in a variety of wave conditions and is co-ordinating Work Package WP3 which is targeted at bottom boundary effects. It is also contributing widely to the other Work Packages - Regular Wave Kinematics (WP1) and Irregular Wave Kinematics (WP2).
The work centres around 10 weeks of testing in the UKCRF at Wallingford. This large facility measures 60m by 30m, has a working water depth of between 0.3m and 0.8m, and includes a 1 in 20 plane sloping beach. A unique current recirculation system is controlled by 4 independent pumps and 80 undershoot weirs, while 72 programmable wave units generate regular or random wave sequences at between 650 and 1150 to the current direction.
The first phase of tests has looked at bottom shear stresses under combined flows, using the UCL Shear Cell to make direct measurements of wave-induced friction. Tests have been performed with water depths between 0.3m and 0.5m and with wave periods in the range between 1.2s and 2.5s in an attempt to increase the wave Reynolds number and thus ensure turbulent flow conditions at the bed. Both monochromatic and random waves were considered, at various angles of incidence to two different steady longshore currents. Velocities were measured using Nortek acoustic flowmeters, with particular interest in the nearbed region where velocity profiles are traditionally used to determine mean shear stresses.
The second phase concentrated on the kinematics and refraction of relatively short waves propagating over a jet-type current with strong horizontal shearing at various angles of incidence, using a water depth of 0.5 m. Wave probes were deployed to determine the height and angle of wave propagation in the flat-bed region, and the Nortek acoustic flowmeters were used to measure all 3 components of the mean and wave-induced velocities through the water column. Regular wave periods of 0.8s and 0.9s were investigated.
The third phase of experiments has been carried
out in the wave-current flume in London, and employed a UCL Shear
Cell to measure shear stresses under co-linear waves and currents.
A new wave generation and absorption system manufactured by Edinburgh
Design Ltd has been installed to provide the wave conditions required
to ensure turbulent flow at the bed and to generate the relatively
long waves necessary to extend earlier work at Delft Hydraulics.
During the project, new data sets have been generated as follows:
Existing data sets have also been used for model validation by the following groups:
Dr Richard Simons has been a lecturer in the Department of Civil & Environmental Engineering at UCL since 1983 and is presently Senior Lecturer in Fluid Mechanics. He has been carrying out research into coastal engineering since 1974 and has made important contributions to the literature on wave-current interaction, many of these papers describing detailed experimental work involving complex flows generated under controlled laboratory conditions. Appointed jointly by HR Wallingford and the UK Engineering and Physical Sciences Research Council (EPSRC) as first Chairman of the "Users Committee" for the Coastal Research Facility (UKCRF) at Wallingford, Dr Simons has been intimately involved in the technical evaluation of the basin since its construction in 1993.
Professor Tony Grass holds a University of London Chair in Fluid Mechanics and has been lecturing at UCL since 1972. His early flow-visualisation experiments revealed fundamental aspects of the structure of turbulent flow which he subsequently used in interpreting the initiation of sediment movement on a mobile bed. During the 1980s Professor Grass was Principal Investigator on a number of offshore engineering research projects, in particular, performing experiments to determine the fluid loading in cylindrical structural elements under the action of combined waves and currents, and researching the performance of pipelines spanning above the seabed or laid on a mobile bed material. He was a member of SERC's influential Coastal Impact Modelling Committee that initiated the present programme of UK EPSRC-funded research into Coastal Engineering, and was Chairman of the UKCRF Facility Management Committee that drew up the specification for the large new wave-current basin at Wallingford.
Ruairi MacIver obtained a degree in Mathematics at Newcastle University and an MSc in Applied Mathematics & Fluid Mechanics at Manchester before moving to Birmingham University to carry out an investigation into the effects of surface films on wave damping. Ruairi was involved throughout the technical evaluation of the new Coastal Research Facility at Wallingford, and has planned and carried out the present experiments on combined waves and currents in the UKCRF.
Bill Fairman has been a Technician in the Civil & Environmental Engineering Department at UCL since 1980. He was responsible for the construction and deployment of the UCL Shear Cell which has been used to make direct measurements of the bed shear stress induced by waves alone, by currents, and by combined multi-directional wave-current flows. He was very much involved in the original design work, and devised methods for setting up the instruments in the UKCRF at Wallingford.
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Start date: 1st February 1996
End date: 30th April 1999
Partners: (this link not yet active)
This page was prepared in January 1999. Any queries to this address please.
