A Zonal CFD Approach for Fully Nonlinear Simulations of Two Vessels in Launch and Recovery Operations

Lead Research Organisation: City, University of London
Department Name: Sch of Engineering and Mathematical Sci

Abstract

Launch and recovery of small vehicles from a large vessel is a common operation in maritime sectors, such as launching and recovering unmanned underwater vehicles from a patrol of research vessel or launching and recovering lifeboats from offshore platforms or ships. Such operations are often performed in harsh sea conditions. The recent User Inspired Academic Challenge Workshop on Maritime Launch and Recovery, held in July 2014 and coordinated by BAE systems, identified various challenges associated with safe launch and recovery of off-board, surface and sub-surface assets from vessels while underway in severe sea conditions. One of them is the lack of an accurate and efficient modelling tool for predicting the hydrodynamic loads on and the motion of two floating bodies, such as vessels of different size which may be coupled by a non-rigid link, in close proximity in harsh seas. Such a tool may be employed to minimise the risk of collisions and unacceptable motions, and to facilitate early testing of new concepts and systems. It may also be used to estimate hydrodynamic loads during the deployment of a smaller vessel (for example, a lifeboat) and during recovery of a smaller vessel from the deck of a larger vessel. The difficulties associated with development of such tools lie in the following aspects: (1) the water waves in harsh sea states have to be simulated; (2) the motion of the small vehicle and change in its wetted surface during launch or recovery can be very large, possibly moving from totally dry in air to becoming entirely submerged; (3) the viscous effects may play an important role and cannot be ignored, and will affect the coupling between ocean waves and motion of the vehicles. Existing methods and tools available to the industry cannot deal with all of these issues together and typically require very high computational resources.

This project will develop an accurate and efficient numerical model that can be applied routinely for the analysis of the motion and loadings of two bodies in close proximity with or without physical connection in high sea-states, which of course can be employed to analyse the launch and recovery process of a small vehicle from a large vessel and to calculate the hydrodynamics during the process. This will be achieved building upon the recent developed numerical methods and computer codes by the project partners and also the success of the past and ongoing collaborative work between them. In addition, the project will involve several industrial partners to ensure the delivery of the project and to promote impact.

Publications

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Bihnam M. (2017) Numerical investigation on effects of compressibility on water entry problems in Proceedings of the International Offshore and Polar Engineering Conference

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Li Q. (2017) Vortex shedding behavior of a horizontal circular cylinder near the free surface with different submerged depths in Proceedings of the International Offshore and Polar Engineering Conference

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Li Q. (2018) Numerical simulation of focusing wave interaction with FPSO-like structure using FNPT-NS Solver in Proceedings of the International Offshore and Polar Engineering Conference

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Li Y (2021) Numerical Simulation of Interaction Between Focusing Waves and Cylinder Using qaleFOAM in International Journal of Offshore and Polar Engineering

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Wang J (2020) Modelling of focused wave interaction with wave energy converter models using qaleFOAM  in Proceedings of the Institution of Civil Engineers - Engineering and Computational Mechanics

 
Description (1) an effective self-adaptive wavemaker technology for 2D and 3D wave modelling; (2) a hybrid model coupling the fully nonlinear potential theory with OpenFOAM; (3) A software package for 3D wave modelling has been built and shared in the wave-structure interaction community; (4) by using the developed technologies, to carry out numerical investigation on two floating bodies in close proximity.
Exploitation Route The development will be merged with other development done by the partners, who jointly applied this project. A open-source software is ready to be released. The end users can have easy access.
Sectors Aerospace, Defence and Marine,Energy,Environment,Transport

URL https://www.plymouth.ac.uk/research/coast-engineering-research-group/lr-nil-a-zonal-cfd-approach-for-fully-nonlinear-simulations-of-two-vessels-in-launch-and-recovery-operations
 
Description The hybrid model developed in this project contributes to the hybrid modelling suite, qaleFOAM, developed at the City, University of London, consisting of multiple fluid and structural mechanics solvers. In the qaleFOAM, the fluid (water and air) near the wind turbines can be modelled using the Navier-Stokes single/two- phase solvers using OpenFOAM with various options of turbulence modelling for both RANS and Large Eddy Simulation, the wave can be simulated using a full spectrum of wave models ranging from linear to fully nonlinear solvers, the blade, tower and foundation can be modelled using rigid body or linear elastic structural solver. Reduced-order models, e.g. ALM and BEM, are also available for modelling the turbine dynamics. Different coupling approaches using the time-splitting (TS), space-splitting (SS) and functional splitting (FS) strategies have been developed and incorporated in the qaleFOAM, allowing different hybrid solvers to be tailored for monolithic or partitioned fluid-structure coupling. By minimising the spatial/temporal domain for high-fidelity and time-consuming solver (the rest will be modelled by faster solvers) whilst maintaining the required degree of accuracy, the qaleFOAM has demonstrated its promising computational robustness in numerical comparative studies (e.g. Venkatachalam et al., 2021) or blind tests (Ransley et al., 2020) for highly nonlinear wave-structure interactions. The code is now released as an open source package through CCP-WSI code repository (https://www.ccp-wsi.ac.uk/code_repository/clearing_house) in github. It receives some industrial interest. Further work with industry partners in the offshore renewables is underway.
First Year Of Impact 2020
Sector Energy
Impact Types Economic

 
Title qaleFoam 
Description A computer code to couple the QALE-FEM with OpenFOAM, qaleFOAM, has been developed and used by academic partners 
Type Of Technology Software 
Year Produced 2020 
Open Source License? Yes  
Impact We are working on the release of the software as open-source code. the impact will be measured using the number of downloads. Specific impact case study is planned as well.