The Flow Around FPSO’s in Steep Regular Beam Waves: Results of PIV Experiments and RANS Computations

Abstract

This paper investigates the hydrodynamical aspects of a fixed FPSO in regular waves. The emphasis is geared to the validation of state of the art CFD techniques, using particle image velocimetry measurements on the water velocities around a captive model of an FPSO in regular waves. The main focus is on the following issues: Determination of the water velocities around the vessel using PIV techniques and pressures on a girth below and just above the mean waterline of the vessel using pressure gauges. Comparison of the detailed RANS simulations of the flow around the bilges of the FPSO. The resulting pressure profiles along the girth, especially near the waterline, showed a significant non-linear effect in steep beam wave conditions. The velocities as measured near the bilges of the vessel indicated a strong separation at the bilges of the vessel. This leads to an overestimation of the water velocities near the bilges of the vessel as calculated using a linear diffraction programme. The resulting pressure profiles along the girth, especially near the waterline, showed a significant non-linear effect in steep beam wave conditions. The velocities as measured near the bilges of the vessel indicated a strong separation at the bilges of the vessel. This leads to an overestimation of the water velocities near the bilges of the vessel as calculated using a linear diffraction programme. RANS simulations will give a more realistic flow profile around the bilges.