Research Topic 1. Heat Transfer in Two-Fluid Flow
Funding: SFI: Basic Research Grant 04 (2004-2008) & RFP 2009 (2010-2014)
Collaboration: Heat and Fluid Flow laboratory at Trinity College Dublin
Post Graduate Training:
PhD Awards: Dr Senthilkumar Sundararaj, 2009.
Current PhD: Abdulaleem Albadawi, from 2010.
The flow of multiple immiscible fluids can be modelled using standard Navier Stokes solvers coupled with interface capturing methods. The Volume of Fluid Method (VOF), in particular, has been extensively researched over the past two to three decades and has been shown to be well suited to a wide range of flow processes. Challenges arise however when surface tension forces become predominant, and when the interface separating fluids with large density ratios interacts with solid surfaces. This is the case for example when air bubbles detach, bounce or slide along solid surfaces. While, this type of flow has been shown to allow very significant enhancement in mixing in general and heat transfer in particular they can be, as a result, difficult to model accurately. Improvements in current numerical methods is the focus of extensive research worldwide and work is being conducted in at the EEFMG in collaboration with the Heat and Fluid Flow laboratory at Trinity College Dublin with a view to validating current models. The objective is to characterise the heat enhancement benefits of certain multi-fluid flow processes and the work relies heavily on HPC in order to study realistic engineering systems. Achievements to date include the development and validation of a coupled Level Set and Volume of Fluid method which has been show to improve substantially the accuracy for capillary dominant flow by comparison with OpenFOAM native solver.
Research Topic 2. Ocean Wave Interaction with Marine Structures
Funding: DCU, School of Mechanical and Manufacturing Engineering
Period: 2010 - Open
The modelling of free surface waves with floating marine structures can be achieved, in principle with the same Navier Stokes VOF methods as discussed in the above research stream. In this case surface tension is not significant, however additional complexities arise from the six degree of freedom motion of the floating structure. This can be accounted for by the solver provided that the computational mesh is allowed to deform. Other effects that would need to be accounted for to model a wave energy devices are (i) the interaction between multiple floating components (ii) external forces which may be due to mooring systems or power take off mechanisms connecting the multiple moving part (iii) a very large computational model to simulate open sea conditions or specific boundary conditions to allow the propagation of waves without reflection. Overall, a realistic system can easily require several million cells to model accurately the system’s dynamic response. The problem is further compounded by the need to refine the mesh near the free surface and over solid surfaces to model correctly turbulence effects. Research is being conducted at the EEFMG to assess the suitability of current software solutions to model the full system and current results are promising.
To see details of simulations, click here
Research Topic 3. The Effect of Fluid Flow on Bio fouling
Period: 2010 - Open
Collaboration: Marine and Environmental Sensing Technology Hub (MESTECH) in DCU
The sensitivity of microbial growth to the micro structure of a range of surfaces is being studied by the Marine and Environmental Sensing Technology Hub (MESTECH) in DCU. Part of this study is considering the effect of fluid flow and resulting shear stresses on the early settlement of bacteria. This work relies on Computational Fluid Flow models of the viscous sublayer extending several hundred micro-meters above the surface and required several million cells. High End Computing is again necessary to achieve accurate solutions.
Research Topic 4. CFD Optimisation of Wind Turbine
Funding: DCU, O’Hare Scholarship
There is a growing demand for electricity production over large parts of the developing world. The rapid spread of mobile phone technology for example is creating a significant need for the supply of energy either to recharge phones or to power network and transmission systems. Of more importance to rural communities is the need for a sustainable source of electricity for the survival and expansion of energy intensive businesses as well as public services such as hospital and schools or community centres. Achieving energy independence can also be a precursor to innovation and the creation of sustainable jobs when no connection to the electricity grid exists. Wind energy is part of the mix of renewable energy that can provide a practical solution towards energy independence by replacing old and inefficient diesel generators. It is also a technology that can be deployed and maintained by local skilled but non-specialised work forces. A wide range of existing projects are helping to train local people to build their own turbines. The Hugh Piggott design for example has been used for training but also to startup businesses and development in this area are growing. The system’s electronic control and the associated energy storage have been shown to be efficiency and cost effective but the turbine blade design involves very limited twist and may benefit from improved aerodynamics. This PhD research will investigate the suitability of state of the art Computational Fluid Dynamics and optimisation solvers to assess potential for improvement. Experimental data including PIV measurements will be used to allow validation.
Research Topic 5. Hydrodynamic and Ecological Modelling of Wastewater Discharge in Coastal Waters
Funding: Proposal Stage
Project Leader: Marine and Environmental Sensing Technology Hub (MESTECH), DCU
Collaboration: Hydraulics and Maritime Research Centre, UCC
Period: Subject to funding
This proposed project is part of a wider study of the urban waste water treatment with a view to improving resource efficiency and minimising impact on the environment. This specific work packages aims to model the hydrodynamic and ecological processes characterising the discharge environment. The modelling work will consider an estuarine environment with multiple discharge points