Awarded a RUBICON postdoctoral grant from the Netherlands Organisation for Scientific Research (NWO) and Marie Curie Cofund Actions, Florent Grasso has joined the Coastal Research Group for two years. His research project investigates “Turbulence and sand transport under breaking waves”.
Summary of research
Extreme storms induce severe beach erosion, endangering human life and infrastructure, and economic resources. Given the anticipated impacts due to the climate change, coastal erosion and its costs are likely to increase significantly in the coming decades. The main problem addressed by this project is the current incapacity of existing coastal-evolution models to predict accurately coastal change during extreme storms. Based on a unique dataset collected by the host, it is postulated that surface-generated turbulence plays a significant role on sand suspension, a process hitherto not considered in existing models. Breaking waves generate vortices that are injected in the water column, hitting the sea bed and stirring sand. The research objective is to develop a thorough understanding of turbulence characteristics associated with high-energy waves and its link to sand transport under breaking waves. The originality and innovative nature of the project rests in a unique combination of field, laboratory, and numerical analyses, to ensure its effectiveness and attainability. It is anticipated that the research outcomes will considerably improve the predictive quality of current operational coastal-evolution models.
Example of a 1000-s time series of near-bed cross-shore velocity u and suspended sand concentration c. Some waves result in high (about 100 kg/m3) concentration peaks, whereas other waves do not, resulting in a highly intermittent concentration signal.
Both series were measured by G. Ruessink using the unique small-scale instrument array (left photograph) under the breaking-wave conditions shown in the right photograph. (Photos: G. Ruessink)
Links
Florent Grasso's website.
Awarded Rubicon grants 15 December 2010.
Please contact Florent Grasso for more information on this project.