Turbulence and the Beach, guest post by Hachem Kassem


Me inBardexII

Hachem surveying the beach in between wave runs during the BARDEX II experiments.



Hachem Kassem, an SMMI PhD researcher based in Ocean and Earth Science, gave a talk as part of the SMMPG seminar series, on turbulence and its role is shaping the beach. His talk, enthusiastically called “Turbulence and the Beach” answered our much sought after question, ‘what does Hachem actually study?’. Attempting to present the most complex problem in classical physics to an audience of non-physicists, Hachem presented ample examples of turbulence in nature and engineering from the daily cup of coffee to the raging storms on Jupiter. Art depicting nature such as van Gogh’s Stormy night, and a selection of historical quotes often highlighting the frustration of those who endeavoured to study this problem, where heavily featured, with quotes like:

Turbulence was probably invented by the Devil of the seventh day of creation (when the Good Lord wasn’t looking (Bradshaw, 1994, J. Exp. Fluids)


‘this area of research has quite a lot in common with studies of alleged paranormal phenomena, precognition, telepathy , ghosts, messages from the underworld, and so on” (McComb, 1990, the Physics of Fluid Turbulence).

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Investigation of Wave Impacts on Porous Structures for Coastal Defences (Robbie Mayon)

This week Robbie Mayon, one of the Southampton Marine and Maritime Institutes’ PhD researchers, spoke with our group about the impacts (literally and metaphorically) waves can have on our coastlines.

We are looking at roughly 1-meter rise in sea level over next 80 years as a best case scenario–worst case being a 2-meter rise, which would lead to over 1 million homes lost in the UK. We therefore must develop and deploy better coastal defence structures and materials if we hope to combat this.

There are four main types of waves: spilling, plunging, collapsing, and surging. Breaking_wave_types

For Robbie, plunging waves are key to his work. When a wave impacts, there’s a large pressure spike, followed by some oscillation afterwards. It is this pressure spike and the oscillations that come after that Robbie is currently modelling to determine what can be done to dampen the effects of these types of waves. He uses OpenFOAM CFD Package to model his waves, using a Dambreak flow simulation.

The main area of concern that he has encountered is air bubbles in the water, as the fluctuations of these bubbles can cause further impacts on the coast (or area that was impacted). His research is focusing in on a way to eliminate these air bubbles, and thus lessening the damage from waves.

Robbie graduated with a BEng degree in Civil and Structural engineering from the University of Aberdeen in 2006, with his dissertation focussing on Finite Element Methods for the design of structural steel connections. Following on from this he worked as a Structural Design Engineer with a consultancy firm based in the British West Indies. In 2014 he obtained an MSc degree in Engineering Simulation and Modelling (First class honours) from Dublin Institute of Technology, Ireland, with his dissertation focusing on investigating the phenomenology of soil liquefaction and subsequent slope failure using the smoothed particle hydrodynamics method.