Strange Experience with DFBI Seakeeping Simulation

Forbin · June 8, 2012, 06:33

Hi there!

Some time ago I had serious problems with my DFBI seakeeping simulation and opened a thread in this forum (http://www.cfd-online.com/Forums/sta...imulation.html).

The help provided there was useful but did not help to completely resolve my problem. In the end I got a similar (working) case from a tutor and compared it to my file. They were identical, except for the mesh and the ship's geometry. Same approach, same settings. Anyway my simulation produced unphysical results.

What saved me in the end?

I wanted to start over again and exported my mesh. I created a new simulation, imported my mesh and set up the properties. In the end I had a new file with the same settings as before.

The weird thing is: It works perfectly!

I compared my files several times: They are identical!
The only difference is: In the first file I created my mesh in Star, in the second file I imported my mesh!

I assume this could be of interest for other users as well, so has anyone a clue what happened?

abdul099 · June 10, 2012, 16:04

Sometimes the sim-file gets messed, although it looks fine. I have absolutely no clue why and how to detect that. But when it happens, it's best to start right from the beginning, like you did.

JeffStrath · April 28, 2015, 16:48

Hi guys,

I am running a CFD seakeeping analysis in head waves and experiencing exactly the same problem with increasing free surface and hence wave damping.

I tried exporting and re importing the file without success. any other suggestions that could lead to similar problems?

Thanks,

Jeff

June 8, 2012, 06:33	Strange Experience with DFBI Seakeeping Simulation	#1
Forbin New Member Join Date: Apr 2012 Location: Germany Posts: 5 Rep Power: 14	Hi there! Some time ago I had serious problems with my DFBI seakeeping simulation and opened a thread in this forum (http://www.cfd-online.com/Forums/sta...imulation.html). The help provided there was useful but did not help to completely resolve my problem. In the end I got a similar (working) case from a tutor and compared it to my file. They were identical, except for the mesh and the ship's geometry. Same approach, same settings. Anyway my simulation produced unphysical results. What saved me in the end? I wanted to start over again and exported my mesh. I created a new simulation, imported my mesh and set up the properties. In the end I had a new file with the same settings as before. The weird thing is: It works perfectly! I compared my files several times: They are identical! The only difference is: In the first file I created my mesh in Star, in the second file I imported my mesh! I assume this could be of interest for other users as well, so has anyone a clue what happened? Last edited by Forbin; June 8, 2012 at 08:14.

June 10, 2012, 16:04		#2
abdul099 Senior Member Join Date: Oct 2009 Location: Germany Posts: 636 Rep Power: 22	Sometimes the sim-file gets messed, although it looks fine. I have absolutely no clue why and how to detect that. But when it happens, it's best to start right from the beginning, like you did. __________________ We do three types of jobs here: GOOD, FAST AND CHEAP You may choose any two!

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April 28, 2015, 16:48		#3
JeffStrath New Member Join Date: Apr 2015 Posts: 2 Rep Power: 0	Hi guys, I am running a CFD seakeeping analysis in head waves and experiencing exactly the same problem with increasing free surface and hence wave damping. I tried exporting and re importing the file without success. any other suggestions that could lead to similar problems? Thanks, Jeff