Statistical Modelling of Current Profiles for a Riser Reliability Design

In the design of risers, current profiles modelling is of great importance. In this paper, various aspects to derive a reliable statistical modelling of currents profiles are considered. First, the reduction of current profiles is treated by mean of the EOF (Empirical and Orthogonal Function) method. In contrast to other studies that have utilized this technique, the information of direction is considered. Secondly, we propose a technique based on B-splines smoothing to identify time series of the different time scales. This can be of utility for a better understanding of some specific events or to improve numerical models. Finally, the efficiency and accuracy of the proposed approach is studied by comparing measured current profiles with those reconstructed from EOF method, by mean of extreme value analysis, using two simple criteria. The first one is based on static calculation and the second is derived from a VIV analysis.