TITLE:
Determination of the Response Amplitude Operator(s) of an FPSO
AUTHORS:
Imabibo Ibinabo, Daniel T. Tamunodukobipi
KEYWORDS:
Response Amplitude Operator(s), Floating Production Storage and Offloading Unit, ANSYS AQWA, MATLAB, Simplified Method
JOURNAL NAME:
Engineering,
Vol.11 No.9,
September
10,
2019
ABSTRACT: The driving necessities of cost reduction and the need to develop fields at ever increasing water depths have led to the use of floating structures. Among these structures are the Floating Production Storage and Offloading (FPSO) units whose motion analysis is considered in this paper. In actual environmental condition, it is required to accurately determine or predict large amplitude motion of the FPSO before any offshore operation. This paper seeks to present a detailed method of computing the Response Amplitude Operator(s) (RAOs) for the six (6) degrees of freedom using ANSYS AQWA. The results indicate for Heave motion a tendency for the heave peak value to move slightly higher dimensionless encounter-frequency as the wave moves from Head sea to Beam sea direction. A MATLAB source code was developed to validate the result for heave motion at head sea. Although a small difference in predicted heave motion occurred, it is pertinent to note that the comparisons between results generated in the MATLAB program and ANSYS AQWA demonstrate generally good agreement, and the roll response of the FPSO is noted to be critical.