Effects of wind forcing on wave overtopping of coastal structures Imperial College London in United Kingdom

The amount of water overtopping a coastal structure and the distance it travels on land are two key design variables for coastal protection structures. Much progress has been achieved in the past few decades regarding the description and estimation of wave overtopping discharges. This has resulted in equations and methodologies that have been widely adopted in industry for the mitigation of coastal flooding (see e.g. EurOtop Manual, 2018).

These parametrisations have largely been derived on the basis of experimental tests using mechanically generated waves in wave flumes or basins. However, ocean waves are generated by the wind, and local winds blowing in stormy conditions may affect the overtopping process at the structure depending upon the type of coastal defence (e.g. rubble-mound breakwater, vertical wall, etc.). For instance, sea spray from breaking waves in the coastal zone is known to travel great distances due to wind forcing. Field evidence indicate that wind can increase overtopping rates significantly. Our limited understanding of its influence can mean that structures might be either under designed or over designed depending upon the consideration of possible amplification of overtopping rate due to wind effects in the design process. This is compounded by the fact that both the distribution of waves and storms is changing due to climate change and future extremes are less well described.

To address the above challenges, the present project will conduct experiments in the wind-wave flume at the Hydrodynamics Laboratory at Imperial. The flume is uniquely designed to provide an accurate representation of the wind profile superimposed on realistic ocean waves. A series of representative coastal structure geometries will be considered and defined after discussion between Imperial and EDF R&D (Electricité de France, R&D division). The evolution of the wind and wave fields, as well as the overtopping characteristics, will be captured using advanced measurements techniques (e.g. Particle Image Velocimetry). Statistics of extreme coastal storms and concurrent winds will be derived from in situ measurements and processed appropriately to produce synthetic forcing conditions to drive the laboratory experiment. A particular attention will be devoted to the scaling of wind effect at model’s scale. One of the targeted deliverables of this research program will be an improved and validated methodology to to take into account the effect of local winds in the estimation of overtopping rates for coastal structures.

The project will be aligned with the Mathematics for our Future Climate CDT , sponsored and co-supervised by EDF R&D. The supervisory team at Imperial includes Dr. Ioannis Karmpadakis (Civil and Environmental Engineering), Dr. Kostas Steiros (Aeronautics) and Prof. Almut Veraart (Mathematics). The research will be performed in collaboration with Dr. Dafni Sifnioti (EDF R&D UK Center, London, UK) and Prof. Michel Benoit (EDF R&D LNHE, Chatou, France) from EDF.

Requirements:

• Undergraduate degree equivalent to UK 1st in Engineering (Civil, Mechanical, Aeronautical), oceanography, physics or similar.
• Advanced knowledge of calculus, statistics and programming (e.g. Python, Matlab, R or other)
• Expertise in experimental methods for water waves or coastal engineering is desirable.
• Excellent communication and reporting skills in English.
• Great attitude towards teamwork.
• Ability to conduct independent research work and curiosity to explore.

How to apply:

Applicants are recommended to contact Dr Ioannis Karmpadakis ( [email protected] ) for further details, informal discussions and information about the project.

Applicants wishing to be considered for this opportunity should send the following application documents to Dr Karmpadakis:

• Current CV including details of their academic record (2 pages maximum)
• Covering letter explaining their motivation, suitability, skills and/or experiences (1 page maximum)
• Contact details of two academic referees

Applications will be regularly reviewed until the position is filled. Administrative questions should be emailed to [email protected] .