How I can get mooring line tension!

Hello everyone,
I am facing some problems while doing mooring line analysis. Problems are:

  1. In MoorDyn dat file (input file) I want the tension load for 20 segment of mooring line. For example, in the output channel i want the tension load for 20 segments of mooring line. (I don’t want FairTen1, FairTen2, FairTen3, AnchTen1, AnchTen2, and AnchTen3).
  2. I have generated a Inflow wind speed of 15 m/s using TurbSim. I want to run the .fst file for 20 min, but it cannot be executed. It shows errors. How can I solve this?
    Could you please give me the answers of these two questions?
    For details please see the attached image.


Dear @JMRaisulIslam.Shohag,

Regarding (1), MoorDyn can output the tension at each node along the line by setting LineOutputs = t; see the MoorDyn v2 documentation here for more information: Input Files — MoorDyn 2.2.2 documentation.

Regarding (2), you should generate wind data from TurbSim for as long as you want to simulate in OpenFAST. It doesn’t appear that you’ve run TurbSim long enough.

Best regards,

Dear Dr. Jonkman,
I have generated wind speed (15m/s) by TurbSim. Then I have modified MoorDyn output as I need 20 segment mooring line tension load.

Please have a look at the MoorDyn output section whether it is right or wrong?


:

I do simulation for 1200 s and time step 0.0125 s. After simulation I have got the tension loads for each node (63 nodes for 3 mooring line). I am calculating the number of cycles.

Now the question is: Will the number of cycles be different for each node tension loads?
N.B: I have got different different number of cycles for each node.

Dear @JMRaisulIslam.Shohag,

Your input file looks fine. And “yes”, different nodes could have different numbers of tension cycles, depending on the system and conditions simulated.

Best regards,

Hi Dr. Jonkman,
I am facing some issues. Could you please help me to solve the issues?
Issues are followings:

  1. When I am setting Recommended module time step (0.5 s) in .fst file then it shows error. please look at the attached file.

Dear @JMRaisulIslam.Shohag,

My guess is that you’ve set the time step of your model too large compared to the system dynamics, resulting in a numerically unstable simulation. Guidance for choosing an appropriate DT can be found in other forum topics.

Best regards,