Virtual Wave Structure Interaction (WSI) Simulation Environment

The project is a close collaboration between STFC-RAL and 2 universities with significant experience in research into wave interactions with fixed and floating structures working together to combine and apply their expertise to model the problem. The aim is to develop integrated parallel code implemented on a massively multi-processor cluster and mutli-core GPUs providing fast detailed numerical wave tank solutions of the detailed physics of violent hydrodynamic impact loading on rigid and elastic structures. The project is linked to and part of a carefully integrated programme of numerical modelling and physical experiments at large scale. Open source numerical code will be developed to simulate laboratory experiments to be carried out in the new national wave and current facility at the UoP.
It is well known that climate change will lead to sea level rise and increased storm activity (either more severe individual storms or more storms overall, or both) in the offshore marine environment around the UK and north-western Europe. This has critical implications for the safety of personnel on existing offshore structures and for the safe operation of existing and new classes of LNG carrier vessels whose structures are subject to large and at present unquantified instantaneous loadings due to violent sloshing of transported liquids in severe seas. There exist oil and gas offshore structures in UK waters are already up to 40 years old and these aging structures need to be re-assessed to ensure that they can withstand increased loadings in increasingly adverse seas as a result of climate change, and to confirm that their life can be extended into the next 25 years. The cost of upgrading existing structures and of ensuring the survivability and safe operation of new structures and vessels will depend critically on the reliability of hydrodynamic impact load predictions. These loadings cause severe damage to sea walls, tanks providing containment to sloshing liquids (such as in LNG carriers) and damage to FPSOs and other offshore marine floating structures such as wave energy converters.
Whilst the hydrodynamics in the bulk of a fluid is relatively well understood, the violent motion and break-up of the water surface remains a major challenge to simulate with sufficient accuracy for engineering design. Although free surface elevations and average loadings are often predicted relatively well by analysis techniques, observed instantaneous peak pressures are not reliably predicted in such extreme conditions and are often not repeatable even in carefully controlled laboratory experiments. There remain a number of fundamental open questions as to the detailed physics of hydrodynamic impact loading, even for fixed structures and the extremely high-pressure impulse that may occur. In particular, uncertainty exists in the understanding of the influence of: the presence of air in the water (both entrapped pockets and entrained bubbles) where the acoustic properties of seawater change leading to variability of wave impact pressures measured in experiments; flexibility of the structure leading to hydroelastic response; steepness and three dimensionality of the incident wave.
This proposal seeks to improve the current capability to directly attack this fundamentally difficult and safety-critical problem by accelerating state of the art numerical simulations with the aim of providing detailed solutions not currently possible to designers of offshore, marine and coastal structures, both fixed and floating.

This project aims the address the important but unsolved issues of wave impact on various marine structures that may be fixed and floating. Examples of fixed structures are jack up platform for oil and gas exploration, offshore wind turbine mounts, coastal defence structures and nuclear plant structures built along coastline. Examples of floating structures are the oil/gas carrier, oil/gas storage and production tankers (such as FPSOs), floating offshore wind energy systems in deepwater, offshore wave energy structures and ships. In many cases, structures have been damaged due to wave impact and slamming. Examples include (1) tearing the bow of Norwegian cruise tanker Wilstar in 1974 (2) bow damage to FPSO Schiehallion in 1998; (3) oil tanker Prestige split into two parts in 2002, causing oil spill disaster. (4) sea wall in the front of Fukushima Nuclear plant hit by the recent Japan tsunami in 2011, causing a nuclear disaster. It can be seen that the issues of wave impact are profoundly safety critical and can reach a broad range of engineering sectors that directly affects society.
Therefore the outcomes of this project, specifically the parallel computer code deliverables will provide much more detailed solutions that currently possible to directly benefit the classification organisations and engineering consultant and service companies. These organisations and companies can use these advanced computer models to improve their standards and designs, and to assess if existing structures will be suitable to serve in the longer term under changed environmental conditions.
The computer codes and more detailed solutions can also be employed by the owners of Liquefied Natural Gas (LNG) tankers, who can use them to assess the wave impact loads on the tank wall due to sloshing waves inside the tank; by the owners of FPSOs, who can use them to assess the weather conditions to see if they would cause damage; by coastal engineering consultancies who may use them to design safer sea walls and coastal defence structures. In addition, they may also benefit the companies who design, manufacture and install the offshore wind energy and wave energy structures as their project designs are based on better understanding of wave-structure interaction physics.
Furthermore, governmental agencies, such as the Health and Safety Executive (HSE) and environment agency (EA), UK, may benefit as well because they can develop better policy to address safety issues related to wave impact on many kinds of structures.
Apart from the above, improved computer models and design methods would provide opportunities for increasing the service and therefore creating additional jobs in the UK and worldwide Oil & Gas, coastal engineering and marine renewable energy sectors, which have been and will continue to be important contributors to UK GDP. It may present a tangible and priceless benefit to the general public in the sense that improved design models and predictions could reduce the risk of failure of a structure, avoiding loss of life and injuries, or could help prevent oil spill or other loss of cargo leading to environmental disaster.
In order to make the impact happen, the proposal is linked directly to current funded projects that will carry out the following activities:
1) Involve key stakeholders (e.g. Lloyds Register, Germanischer Lloyd, Bureau Veritas, Trinity House, Saipem) with an End User Management Group of offshore classification societies and key industrialists in order that they are directly informed of the project achievements;
2) Maintain a website to allow to open access to the information produced;
3) Run project workshops to widen the awareness of these achievements;
4) Run special sessions in International Offshore and Polar Engineering Conference & Exhibition to maximise the international of reach of the developments;
5) Arrange public awareness events so that the interested public is well informed.