Virtual Wave Structure Interaction (WSI) Simulation Environment

Lead Research Organisation: University of Plymouth
Department Name: Sch of Computing, Electronics & Maths

Abstract

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.
 
Description In the project overall, we have shown that it is possible to couple together distinctly different numerical methods within the open-source OpenFOAM environment to create a numerical wave tank which can be used as a comprehensive model for wave-structure interactions.
Exploitation Route Software models being built into OpenFOAM open source solver will be available in open source for academic and industrial users as a numerical wave tank for simulating wave-structure interactions. The findings are currently being used and further developed within the CCP-WSI project EP/M022382/1.
Sectors Digital/Communication/Information Technologies (including Software),Environment

 
Description Outcomes from the current award have informed EP/M022382/1 "A CCP on Wave/Structure Interaction: CCP-WSI". The latter project has subsequently provided extensive training and further resources for industry.
First Year Of Impact 2015
Sector Aerospace, Defence and Marine
 
Description EPSRC Collaborative Computational Projects
Amount £483,159 (GBP)
Funding ID EP/M022382/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 10/2015 
End 09/2020
 
Title OpenFOAM Potential Flow solver 
Description Developed a stable and accurate surface-tracking Potential Flow solver for OpenFOAM to model non-overturning water waves. This will eventually become open-source but is currently being integrated with OpenFAOM incompressible and compressible Navier-Stokes solvers. Eventually, fully integrated numerical wave tank will be produced. 
Type Of Technology Software 
Year Produced 2015 
Impact n/a yet. 
 
Title Virtual Source Method solver 
Description Virtual Source Model is a novel method for modelling non-overturning waves using integral equation methods. Method has been tested in various scenarios and will be developed to integrate with incompressible and compressible Navier-Stokes solvers in OpenFOAM. Abstract outlining method accepted for presentation at ISOPE 2016. 
Type Of Technology Software 
Year Produced 2015 
Impact n/a yet.