Hello everyone,
I am currently seeking some clarification regarding the applicability of the hydrodynamic model implemented in OpenFAST. Based on my limited understanding, the hydrodynamic framework in OpenFAST (specifically within HydroDyn) relies primarily on a potential-flow model formulated under a perturbation expansion framework. When applying the perturbation method to potential flow theory, the fundamental assumption is the existence of one or several small dimensionless parameters. This allows the fluid response and wave-body interactions to be expanded and approximated as power series of these parameters. For floating body dynamics, this typically implies a scale separation: the characteristic dimension of the structure should be larger than the first-order motions, which in turn should be larger than the second-order motions.
My specific question is: how can we rigorously determine whether the floating platform's motions have exceeded these theoretical boundaries? For instance, in a specific sea state, the maximum surge displacement of the IEA 15MW semi-submersible platform reaches approximately 25 meters, while the characteristic geometric dimension of the platform in that direction is around 90 meters. In such a scenario, has the motion already violated the inherent limitations of OpenFAST's potential-flow-based hydrodynamic model?
Some of my understandings might be imprecise or flawed. I would deeply appreciate any corrections, insights, or advice on this matter. Thank you all in advance for your time and expertise!
Sincerely,
marisa
Hello everyone,
I am currently seeking some clarification regarding the applicability of the hydrodynamic model implemented in OpenFAST. Based on my limited understanding, the hydrodynamic framework in OpenFAST (specifically within HydroDyn) relies primarily on a potential-flow model formulated under a perturbation expansion framework. When applying the perturbation method to potential flow theory, the fundamental assumption is the existence of one or several small dimensionless parameters. This allows the fluid response and wave-body interactions to be expanded and approximated as power series of these parameters. For floating body dynamics, this typically implies a scale separation: the characteristic dimension of the structure should be larger than the first-order motions, which in turn should be larger than the second-order motions.
My specific question is: how can we rigorously determine whether the floating platform's motions have exceeded these theoretical boundaries? For instance, in a specific sea state, the maximum surge displacement of the IEA 15MW semi-submersible platform reaches approximately 25 meters, while the characteristic geometric dimension of the platform in that direction is around 90 meters. In such a scenario, has the motion already violated the inherent limitations of OpenFAST's potential-flow-based hydrodynamic model?
Some of my understandings might be imprecise or flawed. I would deeply appreciate any corrections, insights, or advice on this matter. Thank you all in advance for your time and expertise!
Sincerely,
marisa