Modelling of wind-wave interaction for extreme waves

Supervisors

Main supervisor: Dr Shunqi Pan
Co-supervisor(s): Dr Michaela Bray (Cardiff University),Dr Jun Zeng (University of Bath), Dr Judith Wolf (National OCeanograpy Centre),Dr Xiaojun Gu (STFC, Daresbury)

Project enquiries

Email: PanS2@cf.ac.uk
Contact number: +44 29 2087 5694

Host institution: Cardiff University

Project description

For coastal defences and development of marine renewables, predicting coastal waves under storm or extreme conditions is one of the key elements for such infrastructures to operate and preform safely and sustainably. However, accurate prediction of storm waves is highly challenging, only not because of the large spatial scale to be considered, but also due to the strong interaction between wind and waves generated by the surface forcing – wind (Hristov et al., 2003). The nonlinearity of the wave-induced surface friction can affect both the wind distribution near the sea surface and surface waves generated by wind. Examples of the interaction between strong wind and large waves can be seen from the flow in river estuaries, rip currents, entrances in fjords during outgoing tides and in tidal flows in the coastal zone (Peregrine, 1976). To describe the strong interaction between wind and waves, a new current–modified cubic Schrödinger equation (Zakharov & Manakov, 1974) which allows vorticity in the induced flow to be derived can be used in modelling. With a split–step scheme used in the numerical simulations, a first, second, and fourth order scheme can be implemented.

This project is to implement the cubic Schrödinger equation, into the advanced modelling framework which couples the oceanic hydrodynamic model POLCOMS/PROWam (Zou et al, 2013) and the weather model WRF to investigate in detail the wind-wave interaction and its impact on the extreme wave prediction. The 3D mode results also allow the flow structure, baroclinic instability and turbulence mixing to be examined for applications of coastal defence structures and marine renewable devices.

The project is expected to 1) improve the understanding wind-wave interaction under storm/extreme conditions; 2) develop and implement the improved algorithm to the integrated modelling framework; 3) validate the modelling framework with the experimental and field data; 4) improve the prediction of the extreme waves; and 5) apply the improved modelling system to both offshore and nearshore structures.

References

Hristov, T. S., Miller, S. D. & Friehe, C. A. (2003), Dynamical Coupling of Wind and Ocean Waves through Wave-Induced Air Flow, Nature 422(6927): 55-58.

Peregrine, D. H. (1976), Interaction of water waves and currents in “Advances in Applied Mechanics 16”, Academic Press, 9–117

Zakharov & Manakov (1974), On the complete integrability of a nonlinear Schrödinger equation. Journal of Theoretical and Mathematical Physics 19 (3): 551–559

Zou, Q.-P., Chen, Y., Cluckie, I., Hewston, R., Pan, S., Peng, Z. & Reeve, D. (2013), Ensemble Prediction of Coastal Flood Risk Arising from Overtopping by Linking Meteorological, Ocean, Coastal and Surf Zone Models, Quarterly Journal of the Royal Meteorological Society 139(671 Part B): 298-313.

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