Estimation of Wind and Current Load on Offshore Structures Using Wind Tunnels and CFD

Abstract

Abstract This paper suggests the improved technology to predict the wind and current loads on offshore structures such as FPSO and Semi-submersible. Wind tunnel tests and CFD analysis are conducted and results and application methods are discussed. The characteristics of flow and extrapolation to real Reynolds number condition are also analyzed with regard to loads. To analyze the load and flow characteristics, the detail conditions of wind tunnel and CFD are investigated such as flow field and model setup and their effects on results are examined. From the comparison of wind tunnel tests and CFD, flow physics are analyzed regarding the characteristics of the flow. This paper shows the parameters which affect the wind tunnel tests and explain the reason of differences between wind tunnel tests and CFD. The flow field such as velocity profiles and turbulence is major parameter and model setup and test condition must be described as accurate as possible. The additional and new consideration for wind tunnel test is suggested based on observed results. The flow around semi-submersible differ from FPSO and different approaches are necessary considering flow characteristics. The extrapolation to real Reynolds number condition is very difficult for the offshore problem. Based on above results, the extrapolation is discussed for the estimation of wind and current loads on FPSO and Semi-submersible. The results show that new suggestions of wind tunnel test give the improved prediction and reduce the uncertainties. CFD analysis considering wind tunnel environment give more reliable results and extrapolation may afford more efficient and conservative estimation of wind and current loads. This may significantly influence the design of mooring system and offshore structure.