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An empirical time-domain (TD) vortex-induced vibration (VIV) prediction model has been implemented in a software called VIVANA-TD based on its earlier development by Thorsen at NTNU. It models the synchronization of VIV loads and structural responses with a set of empirical parameters generalized from model tests. Combining this time domain hydrodynamic load model with a non-linear finite element structural model makes it possible to account for structural non-linearities and time-varying flow. A joint industry project (JIP), i.e., Lazy Wave Riser JIP has been organized to improve the design basis for SLWRs. This JIP is executed by SINTEF Ocean with support from NTNU. The industry participants are Equinor, BP, Subsea7, Kongsberg Maritime and Aker Solutions. The overall objective of this JIP is to systematically validate VIVANA-TD, in order to establish it as an industrial tool for VIV prediction. It is also aimed to improve the empirical basis and methods for calculation of VIV of deep-water steel lazy wave risers (SLWRs). In the present paper, the validation study is presented for selected model tests in constant flow conditions with uniform and sheared profiles. The test model includes bare pipe, pipe with partial strake coverage and riser model with staggered buoyancy elements. The empirical parameters have been generalized based on extensive model test data. Limitations and improvement of the model have been also been explored. The results show that the present TD model can represent reasonably the VIV loads and that the prediction has good agreement with measurements in general.

Marine drilling riser is subject to complicated environmental loads which include top motions due to mobile offshore drilling unit (MODU), wave loads, and current loads. Cyclic dynamic loads will cause severe fatigue accumulation along the drilling riser system, especially at the subsea wellhead (WH). Statoil and BP have carried out a comprehensive model test program on drilling riser in MARINTEK's Towing Tank in February 2015. The objective is to validate and verify software predictions of drilling riser behavior under various environmental conditions by the use of model test data. Six drilling riser configurations were tested, including different components such as upper flex joint (UFJ), tensioner, marine riser, lower marine riser package (LMRP), blow-out preventer (BOP), lower flex joint (LFJ), buoyancy elements, and seabed boundary model. The drilling riser models were tested in different load conditions. Measurements were made of microbending strains and accelerations along the riser in both in-line (IL) and crossflow (CF) directions. Video recordings were made both above and under water. In this paper, the test setup and test program are presented. Comparisons of results between model test and RIFLEX simulation are presented on selected cases. Preliminary results show that the drilling riser model tests are able to capture the typical dynamic responses observed from field measurement, and the comparison between model test and RIFLEX simulation is promising.