Swansea University Excellence Research Scholarship: Extreme Wave Interaction with Rubble Mound Breakwaters: a Hybrid Numerical Model with Experimental Validation
Swansea University is proud to offer 15 fully-funded PhD scholarships for students commencing study in October 2018 or January 2019.
The scholarships will be awarded on the basis of student excellence across a portfolio of 34 potential projects.
Rubble mound breakwaters have been used extensively in coastal regions to protect ports and shorelines. Engineers design/maintain rubble mound breakwaters mainly on the basis of scaled physical model tests and empirical formulae. Despite testing, unexpected damage to breakwaters still occurs due to extreme waves. This makes the maintenance of existing and design of new rubble mound breakwaters troublesome, because of the ill-defined nature of destructive environmental forces. Studying all extreme scenarios experimentally would be ideal, but is impractical because of the constraints in budgets, time and laboratory facilities. Thus an accurate and efficient modelling of extreme wave interactions with breakwaters would provide an efficient and sorely needed tool for engineering applications.
Numerical studies of extreme wave impacts on breakwaters are very limited because of the great difficulty in handling the rapidly changing domain and discontinuity of fluid motion (e.g. in the case of wave breaking upon impact). Another challenge is to model the rubble mound units of irregular shapes, whose interactions with water are complex. To address this knowledge gap, the aim of the PhD project is to develop an accurate and efficient numerical model by combining two novel particle-based numerical methods (that have intrinsic advantages in handling wave impacts and solid objects), to investigate the extreme wave interaction with rubble mound breakwaters.
Available Resources/Facilities and Research Approach:
1. A hybrid numerical model combining two novel particle methods: The project supervisors have developed a new particle-based numerical model called the Consistent Particle Method (CPM), which incorporates several novel ideas and parallel computing, and is capable of predicting highly-deformed waves and violent wave impacts (5 high-rank publications are listed on the webpage of the first supervisor). Hence the CPM will be used as the fluid solver to model violent ocean waves. For the modelling of a rubble mound breakwater, the open-sourced Discrete Element Method (DEM) - CFDEM@project (www.cfdem.com/) will be utilized and improved if necessary. The DEM model will be coupled with CPM to simulate violent wave impacts on a rubble mound breakwater and the responses of the breakwater. An efficient coupling algorithm will be developed to combine these two meshless methods. Specifically, in each computation step the solid units are the boundary of the fluid domain and the fluid applies forces to solid units. The main challenge is to generate virtual particles on the irregular solid surfaces. These virtual particles will be treated in the same way as fluid particles to compute the fluid pressures acting on them, integration of which is part of the external forces applied on the solid units. To address this challenge, a new advanced boundary treatment scheme will be developed to model complex solid boundaries, which is still an open issue in particle method simulation. The high performance computer cluster in the College of Engineering will provide strong supports to the proposed numerical work.
2. Experimental validation: In studies of complex extreme wave impact, it is crucial to validate the numerical model by experimental data. Hence, laboratory-scale experiments will be conducted in the wave flume of the Coastal Lab of the College of Engineering. The global parameters such as wave height and overtopping discharge as well as localised flow properties including fluid velocity in the interstices of rock units (which has rarely been studied) will be measured using the state-of-the-art measuring devices (Particle Image Velocimetry, Laser Doppler Anemometer and high-resolution pressure sensors). The data will be used to demonstrate the capability of the coupled CPM-DEM model to reproduce violent coastal waves, impact forces and the possible failure of a rubble mound breakwater. Using the validated CPM-DEM model, the actions including impulse forces of extreme waves on rubble mound breakwaters will be investigated. Parametric studies on the shape of breakwater section and size and shape of rubble mounds will be conducted to give recommendations for engineering design.
Projected Research Outcome
The key outcome of this research project will be the development of a powerful meshless numerical model to simulate complex water-solid two-phase flow problems in coastal engineering which also has great potential for application to river and geotechnical engineering problems. The intention is to make the code open source and integrate it into the ZCCE software platform to enhance potential impacts. The laboratory data will also serve as an important supplement to the existing coastal engineering community experimental/field database.
Supervisor / Academic contact: Dr Min Luo
The successful applicant will also have access to our Postgraduate Research Student Training programmes.
Candidates should have (or expect to obtain) a first class honours degree (or equivalent) and/or a master's degree with distinction in a relevant subject area, such as civil engineering or other cognate disciplines.
Applicants should have experinece of numerical simulation and Fortran/C/C++ programming. Knowledge of PIV setup and operation experience is desirable.
Due to funding restrictions, this scholarship is open to UK/EU candidates only.
The scholarship covers the full cost of UK/EU tuition fees and an annual stipend of £14,553 for 3 years.
There will also be £1,000 per annum available for research expenses such as travel, accommodation, field trips and conference attendance.
Please visit our website for more information.