Dear Sir/Madam,
Currently, I'm working on creating a hexagonal Single Point Mooring model in MOSES EDITOR. I need to form the compartment model inside the SPM.
Since the SPM has a hexagonal form, thus the compartment has to be a Triangular Prismatic as you can see in the attached figure below. I found it difficult to create the triangularly prismatic form if I use plane command.
Is there any alternative method that can be used for this work?
Thank you in advance.
Here's the example of my build up command:
&dimen -save -dimen Meters M-Tons&describe body COBAPRISMA&describe Body Tank001pgen -PERM -1 -PORT -LOC 0.00 0.00 0.00 -diftype NONE plane 0 -cart 0.00 0.00 3.474 0.00 3.474 5.641 plane 6.0040 -cart 0.00 0.00 0.000 0.00 0.000 5.641end pgen&describe Body Tank002 pgen -Perm -1 -LOC 0.00 -3.474 0.00 -diftype NONE PLANE 0 -cart 0.00 0.00 0.000 0.00 0.000 5.641 plane 6.004 -cart 0.00 0.00 3.474 0.00 3.474 5.641end_pgen
Hi Hanif,
I attached a wedge.zip. This is a set of file that show how to make a wedge or triangle shape compartment. Please run spar.cif before running c_spar.cif.
Please review and let us know your questions.
Kind regards,
Georgina Maldonadowedge.zip
Hi Georgina,
Your code worked really well, thank you.
Yet, I do have another question,
While I am using the 'difference' command to make a hole inside of the body, why cannot I generate the hydrodynamics command in order to obtain the RAO? Is it because of the 'difference' command not generate the closed surface?
Thanks in advance.
Please add the line
&describe piece Pname -ditype 3ddif -cs_curr 1 1 1 -cs_wind 1 1 1
before the panel definitions. In the above command "pname" is the piece name.
Also the command "INMODEL" does not need the body name after it. The command is simply "INMODEL".
I hope this helps. Please let us know of other questions.
Georgina Maldonado
Dear Georgina, thanks for helping me!
However, if you don't mind, I would like to ask another question,
After the hydrodynamic analysis was generated (I was using 3ddifraction theory), why is it so difficult to find the equilibrium of single point mooring (calm buoy) for mooring analysis during the time domain simulation?
You give me very little to work with. Can you tell me more about your difficulties?
Have you included a mooring system? Is the equilibrium including a wave environment? What is the warning message?
Thank you,
I have attached the mooring lines to the buoy. However, the equilibrium positions were not found in 2 conditions: first, after the command &dcptime, second, after the environmental data were generated (after &env command). The warning message said that "the simulation terminated due to instability". Are these problems occurred because of the mooring arrangement or any something else?
I have attached my build-up command that might be evaluated by yourself.
ps: Please ignore the post-processing command, because I haven't fixed that yet.
calmonly.rar
Hello Hanif
The files you sent do not show the mooring system characteristics. I am sending back the command file with the commands to review the mooring system characteristics.
The mooring system defined put the anchors 330 m from the fairlead. This results in the mooring system lines not having a catenary shape. Most mooring are dependent on the force changing when the catenary shape changes.
The environment defined has a mean wave force of 72 mtons. The mooring system restoring force shows a very steep slope for the restoring force to counter 72 mtons. The steep slope is why you are having problems finding equilibrium.
Please review and let me know if you have further questions.
calmonly.zip
Hello Georgina,
Please i am having the same issue. I have downloaded the folder you sent to Hanif. Which folder do i add this comment "&describe piece Pname -ditype 3ddif -cs_curr 1 1 1 -cs_wind 1 1 1" Because when i run dynamics because RAOS were all 0 0 0 etc. I am basically trying to generate RAOs for a SPM Buoy using the folder you sent as a guide.
Hi Amarachi,
Could you please explain what you are trying to accomplish? This thread dates back to 2019 and has had many files sent back and forth. Therefore, when you reference them, it's difficult to determine which ones you are referring to. I suggest either creating a new thread or clearly defining your problem so that I can assist you effectively.
The '&describe piece' command should be in the model file where you define the vessel hull geometry.
Please let me know your specific problem so that I can provide better assistance.
Thanks,
Rahul Kanotra
Hi Rahul,
thanks for responding. My specific problem is that I am unable to obtain RAOs of the BUATFORUM.Rar folder sent by Hanif to Georgina above. Please Rahul can you suggest what I can do to obtain RAOs of the Spar buoy modelled already?
Dear Amarachi,
I have reviewed the buatforum.rar file, which utilizes the &surface menu to create spar geometry. However, you should know that the &Surface menu in MOSES has been deprecated. To create geometries using boolean operations, you can use the MOSES Modeler included with the MOSES installation.
Since you wanted to understand how RAOs are calculated in MOSES, I have prepared sample files for a 300m barge, calculated the RAOs, and generated plots. Please have a look at the syntax and feel free to reach out if you have any further questions. Please create a new post for further questions on MOSES.
Regards,
4403.RAO.rar