Predicting motions of deepwater platform based on the inverse reconstruction of environmental loads

In hybrid model testing technique, model tests are primarily used to verify numerical models which is used to predict the responses of full-depth systems. However, hybrid model testing method based on potential flow theory highly rely on the accuracy of mathematical model, facing challenges in accurately predicting full-depth responses with viscous effects, such as flow-induced motion. To solve the problem, a method for predicting motions of full-depth system is proposed based on the inverse reconstruction of the environmental loads from the truncated model test, considering viscous and nonlinear effects on platform. To validate the method, a series of model tests were conducted for a semi-submersible platform in head seas using both truncated and full-depth mooring systems to validate the method. The environmental loads could be extracted accurately via the inverse reconstruction method under different environmental conditions, including 100-year-return-period wave-only, current-only, coupled wave, wind, and current conditions. The results of time history, statistics, and power distribution show that the proposed method has better performance than conventional method of hybrid model test in situations where viscous effects are obvious.