Mooring system damping

Wind & Water Computer-Aided Engineering Software Tools
1

Dear Jonkman,
I want to connect a damper in series on the mooring line of the open fast mooring system module. How can I achieve this?

Best regards,

2

Hi @Cuizhi.Zhu,

MoorDyn has a built in damping model that should work for what you need. It is a parameter of line types, called BA. You can read more in the docs: Input Files — MoorDyn 2.3.1 documentation

Are you looking to implement damping within the mooring line or to add a damper in-line with a mooring line?

3

yes i want add a damper in-line with a mooring line

---- Replied Message ----

From | Ryan Davies via NREL Forumnotifications@nrel.discoursemail.com |

  • | - |
    Date | 09/10/2024 23:48 |
    To | cuizhizhu2022@163.com |
    Cc | |
    Subject | [NREL Forum] [Wind & Water/Computer-Aided Engineering Software Tools] Mooring system damping |

| Ryan.Davies
September 10 |

  • | - |

Hi @Cuizhi.Zhu,

MoorDyn has a built in damping model that should work for what you need. It is a parameter of line types, called BA. You can read more in the docs: Input Files — MoorDyn 2.3.1 documentation

Are you looking to implement damping within the mooring line or to add a damper in-line with a mooring line?

4

Hi @Cuizhi.Zhu,

I would suggest then modeling the damper in MoorDyn as a separate short line element with the damping properties you need, while your mooring lines have their independent properties from the damper.

5

May I ask if I want to add a damper structure string to connect the mooring cable, can it be achieved through the MoordynC coupling module？

6

Hi @Cuizhi.Zhu,

The damper in line with a mooring line can be done with either MoorDyn-C or MoorDyn-F, they are internally the same. How do you plan to use MoorDyn? If it is in OpenFAST then you will be using MoorDyn-F, that is the OpenFAST internal mooring dynamics module. The documentation might provide some clarity: MoorDyn - Lumped-Mass Mooring Dynamics — MoorDyn 2.3.1 documentation

7

Hi Ryan.Danies

image
image926×411 81.4 KB

I want to implement it through this orcaflex, is it also through this file" FASTlinkDLL.dll"?

8

Hi @Cuizhi.Zhu,

While I am not familiar with the OrcaFlex-FAST coupling (it was done before I began work on OpenFAST), the description you provide states that OrcaFlex handles all the hydrodynamic and mooring loads while FAST handles the other loads. I am a bit confused how you would implement something from MoorDyn, as OrcaFlex is taking the place of MoorDyn in the coupling.

9

Hi Ryan.Davies,

I plan to not use the Moordyn module of OpenFast and instead use Orcaflex instead of Moordyn