The offloading operability is one of the key design parameters of a Floating Liquefied Natural Gas (FLNG) cargo design. Therefore, the uncertainties in offloading analysis can lead to unnecessary conservatism in the cargo design of a FLNG which increases CAPEX. Furthermore, overprediction or underprediction of the offloading operability increases uncertainties for evaluating production downtime and OPEX.A side-by-side moored offloading configuration has relatively stronger hydrodynamic and mechanical interactions compared to a tandem moored offloading configuration. For instance, due to the narrow gap between FLNG and LNG Carrier, the trapped water resonance induces higher relative motions between the FLNG and LNG Carrier. In addition, due to the partial filling conditions during the offloading operations, the sloshing loads excite ship motions which induce higher loading on the offloading arms. Therefore, the development of a reliable analysis software, which can analyze hydrodynamic interactions, mechanical couplings and sloshing-ship motion coupling effects, is crucial for accurately predicting the side-by-side moored offloading operability.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;In order to improve analysis accuracy of the multiple floating platforms interactions, several researchers have studied the hydrodynamic interactions and mechanical couplings between multiple floating platforms. Koo, et al. conducted a time domain fully coupled multi-body analysis in side-by-side offloading operations [1] &amp; [2]. Molin, et al. carried out experimental and numerical study on gap resonances in between two rectangular barges [7]. Koo, et al. conducted a tandem moored FPSO offloading analysis to evaluate hydrodynamic interaction effects using combined matrix method and separated matrix method [3]. Recently, Koo, et al. conducted a time domain offloading operability analysis for the full 35 years’ service life of a FPSO using High Performance Computing (HPC) [8]. On the other hand, several researchers have studied the sloshing-ship motion coupling effects. Kim et al. [4] and Kim et al. [6] conducted analysis for the sloshing impact load on the cargo tank wall, and Lee et al. conducted a time domain global performance analysis for a LNG carrier including tank sloshing effects using CFD and 3D radiation/diffraction solvers [5].In this research, a time domain sloshing-ship motion coupling analysis module has been developed for analyzing interactions of the side-by-side moored multiple floating platforms. In order to validate newly developed sloshing-ship motion coupling analysis module, systematic code to code validations have been conducted for a LNG carrier and side-by-side moored FLNG and LNGC.This paper will present the numerical modeling, the validation analysis results, and the sloshing-ship motion coupled effects on the side-by-side offloading analysis.&nbsp;&nbsp; &nbsp;References.[1].&nbsp;&nbsp; "Hydrodynamic Interactions and Relative Motions of Two Floating Platforms with Mooring lines in Side-by-side Offloading Operation". Journal of Applied Ocean research, Vol. 27, pp 292-310.[2].&nbsp;&nbsp; "Global Analysis of FPSO and Shuttle Tanker During Side-by-Side Offloading, Final Project Report Prepared for the Minerals Management Service Under the MMS/OTRC Cooperative Research Agreement". 1435-01-99-CA-31003, Task Order 73604, MMS Project Number 488.[3].&nbsp;&nbsp; "Motion analysis of two floating platforms with mooring and hawser lines in tandem moored operation by combined matrix method and separated matrix method", Journal of Ocean Engineering and Technology, Vol. 19/5, pp 1-15.[4].&nbsp;&nbsp; &nbsp;“Sloshing-Ship Motion Coupling Effect for the Sloshing Impact Load on the LNG Containment System”, ISOPE 2005[5].&nbsp;&nbsp; &nbsp;“The effects of LNG-tank sloshing on the global motions of LNG carriers”, Journal of Ocean Engineering, Jan 2007.[6].&nbsp;&nbsp; &nbsp;“Numerical simulation of sloshing flows with impact load”, Applied Ocean Research 23, 53-62.[7].&nbsp;&nbsp; &nbsp;“Experimental and numerical study of the gap resonances in between two rectangular barges”, IMAM 2009[8].&nbsp;&nbsp; "Direct Time Domain Simulations for a FPSO Tandem Offloading Operation" OMAE2019-96638

Sloshing Effects on Flng and Lngc Side-by-Side Offloading

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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