CFD Truss Spar Hull Benchmarking Study

Blind comparisons of computational fluid dynamics (CFD) predictions are made against large scale experiments of a truss spar hull. The overall objective of the work is to try and mature CFD modeling capability related to motion and loads for offshore platforms. Specific goals include the testing of newly developed meshing techniques and seeking an understanding of how spar appurtenances interact. The key comparisons are illustrated in comparisons of the simple case of a spar hull with stakes alone against a second, far more complex case, involving multiple appurtenances. The latter exhibits very different vortex induced motion (VIM) behavior. The CFD predictions were made with knowledge of the as-built model details, but without access to the experimental results. The estimates were found to be in close agreement with the experiments or slightly conservative. We continue to observe that the better the model fidelity, the better will be the comparison with the benchmark. The computations show that high quality predictions are now feasible, given access to sufficient computational hardware and accurate meshing of the body in question.