A vortex induced motion (VIM) study to determine the sensitivity of the VIM response to the geometric parameters of deep draft semisubersibles, computational fluid dynamics (CFD) analysis to understand semi-submersibles' VIM and sensitivity to various parameters by studying the fluid flow (i.e. vortex shedding and wake interface) and VIM response to be used in the development of guidelines, and a model test to validate the VIM performance of one benchmark semi hull configuration and several variations in VIM mitigation options in a towing tank, with and without suppression devices.

The research will be conducted in two phases:

The VIM study and CFD analysis was conducted for an ultra-deepwater dual column dry tree concept and a second deep draft concept developed by Aker (DTS Floating System), both of which are undergoing further evaluation for suitabilitiy (in RPSEA Project 10121-4404-02). The study may result in changes to VIM suppression strake designs, column geometry modifications, and/or improve the VIM performance of sixteen (16) semisubmersible designs based on two hull types (paired column and conventional), with eight variations in column and node configuration (shape, spacing, and orientation) (TRL1)

The model test resulted in VIM suppression devices or hull geometric optimization recommendations with due consideration to the platform global performance and constructability (TRL2) This work will complement project 10121-4405-02 research and will, by virtue of determination of the strengths and weaknesses of the paired columns and the conventional semi systems, contribute to the decision to down-select a concept.