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Details of Grant 

EPSRC Reference: GR/R23619/01
Title: Non-Linear Wave-Current Interactions: the Effects of Vorticity On Extreme Waves
Principal Investigator: Swan, Professor C
Other Investigators:
Baldock, Dr T
Researcher Co-Investigators:
Project Partners:
Department: Civil & Environmental Engineering
Organisation: Imperial College London
Scheme: Standard Research (Pre-FEC)
Starts: 01 January 2001 Ends: 30 June 2004 Value (£): 176,088
EPSRC Research Topic Classifications:
Coastal & Waterway Engineering
EPSRC Industrial Sector Classifications:
Water No relevance to Underpinning Sectors
Related Grants:
Panel History:  
Summary on Grant Application Form
The proposed project concerns the nonlinear interaction of waves and currents. In particular, it addresses the case of large transient or unsteady waves arising in a random sea interacting with rotational currents in which the vorticity distribution is non-uniform. If one includes the effects of directionality, both in the wave field alone and within the combined wave-current field, this represents wave-current interaction in its most general form. Such flows commonly occur in both the offshore and the coastal engineering environments, but cannot be described by existing wave-current formulations. As a result, the significance of the vorticity distribution remains uncertain, as does the maximum crest elevation (for a given wave height), the extent of local energy shifts due to the nonlinear interactions, and the extreme water particle kinematics including both velocities and accelerations. To investigate these factors the project will initially consider 2-D flows in which the wave and the current are co-Iinear. New experimental studies will provide the first quantitative measurements of extreme transient or focused wave groups (NewWave-type simulations) on vertically sheared currents, typical of those generated by an overlying wind flow. New modelling procedures, based on the Green-Naghdi theory of fluid sheets, will also be developed. The results of a feasibility study, on which the present proposal is based, suggests that this model is uniquely capable of describing the complete wave-current interaction, including the 'gradually-varying' problem when the evolving waves first propagate onto the current profile. Having validated the 2-D model, the theory will be extended to include the effects of directional spreading. A fully nonlinear 3-D wave-current model capable of including arbitrary vorticity , represents an important practical goal. Comparisions with an existing 3-D potential flow model, capable of including the nonlinearity but restricted to irrotational wave motion, will allow initial verification. Once complete, the full nonlinear, 3-D, rotational wave-current model will be applied to a range of practically important flows. These will include the interaction of extreme 3-D ocean waves with wind-driven currents and the complex 3-D interactions which dominate the coastal zone, particularly in the vicinity of a river outflow. In this latter area comparisons with state-of-the-art laboratory data observed within the UK CRF is planned.
Key Findings
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Potential use in non-academic contexts
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Further Information:  
Organisation Website: http://www.imperial.ac.uk