The floating object tutorial
 

Hi,

i am trying to get a case with floating objects running. Therefore i took several looks at the floatingObject tutorial coming with interDyMFoam.
When i run this tutorial single-core it works and finishes. But when i use decomposePar to split the case on 4 cores it crashes at 1,8s case time.
This is reproducible. It happens on my virtual machine hostet by Win7 and also on my pure Kubuntu machine.
OpenFoam in version 2.1.0 64Bit

This is happening no matter which decomposition method i am using. I used scotch and it crashed at 1,8s case time. When i use the decomposeParDict coming with the tutorial (using hierarchical decomposition) it crashes at 2s case time.

What is happening there?
Any suggestions how to get this fixed?

Thank you!
Greets
Leech

I found a workaround for the problem. They wrote: "There is a problem with the decomposition of point fields (i.e. pointDisplacement).Decompose the mesh before copying 0.org to 0 in each processor directory, so the pointDisplacement field is not operated on by the decomposition"

I tried to do it, but interDyMFoam cant run. I am using this script:

interFoam says:

I guess i confused something in the script, the order is incorrect.
Someone can help me with that?

Thanks!

Hi Leech,

Add this entry to "0.org/pointDisplacement":
Here's the modified "Allrun" script:
Nonetheless, this doesn't fix the problem.

I've tried reducing the Courant limiters in "system/controlDict". I've tried reducing the relaxation factors and tweaking the PIMPLE parameters and ... no dice. I'm in no way an expert at this, but since others have also tried and failed, even with the 1.7.x version, I suggest that this might be categorized as a bug.

I suggest that you try filling another bug report on this subject: http://www.openfoam.com/mantisbt/my_view_page.php

Best regards,
Bruno

Thanks for your work Bruno!
I reported the bug: http://www.openfoam.com/mantisbt/view.php?id=401

Hi Leech,

I've noticed your bug report before I saw your post here ;).

I've also tested the complete workaround that was given in OpenFOAM 1.7.x, on 2.1.x, but with no success either.

Nonetheless, the complete adaptation would be:

• The Allrun script should contain something like this:
  Code:

  ---

  #!/bin/sh
cd ${0%/*} || exit 1    # run from this directory

# Source tutorial run functions
. $WM_PROJECT_DIR/bin/tools/RunFunctions

# Set application name
application=`getApplication`

runApplication blockMesh
runApplication topoSet
runApplication subsetMesh -overwrite c0 -patch floatingObject
#cp -r 0.org 0 > /dev/null 2>&1
#runApplication setFields
#runApplication $application

runApplication decomposePar

for proc in processor*
do
  cp -r 0.org $proc/0 > /dev/null 2>&1
done

runParallel setFields 4
runParallel $application 4

#runApplication reconstructPar

  ---

• The remaining fixes to the files at "0.org" are shown here: https://github.com/OpenCFD/OpenFOAM-...97d7b65de5eef1

Best regards,
Bruno

Hey,

as I am trying to build a case with floating objects i now switched to singlecore as long as there is no fix. I got a different very confusing problem at this point.

I changed the floatingObject tutorial just a little bit (changed the box to a different size and adjusted the water height and the position of the floating box and the mass centre of the box). I even removed the pile of water crashing down, as i later want to make the waves by waves2Foam (or groovyBC).

When i run interDymFoam in singlecore-mode now it crashes immediately after 2-3 steps. I just cant figure out why. My floating case i made also crashes, thats why i thought i try the tutorial as base and change it in little steps. But as i change one little thing it crashes.
Maybe someone wants to take a look at it, i will attach it. For any tips thank you sooo much!
I am getting hard angry is i am trying to get this floating-thing to work since 4 weeks now and my boss wants to see something in the near future :)

So thank you!
Greets
Leech

hydrodynamics analysis(under water)
 

Dear friends,
i am doing analysis in under water hydrodynamics,i design one simple model in catia like 3D rectangular box,with flap,i dont how to start i want to know how to import that 3D model in open foam and how to mesh ,how to set boundary condition that is medium is water not air,what kind of solver i can choose for example in commericial software we do as to put outer domain inside cad model and set boundary conditions, meshing and to write udf for that flap,and compute in fluent and get results,these all work how do in openfoam,please kindly guide me as soon as possible for your valuable time spending in this area

Dear All,

Have you had any luck getting the floatingObject tutorial to run in parallel? I have try the methods posted above and it runs but the box just sinks and the simulation crashes. Any tips on how to get this to run in parallel would be much appreciated.

Thanks,

Ed

Greetings Ed,

AFAIK, with this case, consider yourself lucky if it doesn't crash in serial!

The following bug report as not yet been fixed: http://www.openfoam.org/mantisbt/view.php?id=417

Nonetheless, you can try the schemes mentioned on these posts:

• http://www.cfd-online.com/Forums/ope...tml#post400972 post #7
• http://www.cfd-online.com/Forums/ope...tml#post293988 post #43

Best regards,
Bruno

Thanks Bruno for the information. I have encountered an error while the solver is solving for the cellDisplacement, did I do anything wrong?

EDIT* when relaxing the tolerance to 0.05, it runs longer, several timesteps before the error.

Greetings haze_1986,

Honestly, I suggest that you upgrade to the latest OpenFOAM version. The version 2.1.0 is very likely to have had issues with the floating object tutorial, when small changes were made to the tutorial. And I'm not familiar with a "groovyFloatingObject" tutorial, but if it came from swak4Foam, then it might not be fully up-to-date either.

Best regards,
Bruno

Greetings Bruno,

Would you recommend to use 3.0extend or 2.3.0? Thanks.

Hi haze_1986,
Honestly, I suggest you install both. I'm not sure about the status of the floating object in either versions, but having both can come in handy, sooner or later.

Best regards,
Bruno

3d FSI dynamicfvmesh
 

Hi,haze! I'm using foam-ext-3.0 to simulate 3d FSI problem. when i run in parallel,I encounter the same problem as you mentioned: "face area doesn't match neighbour ...." . It can work fine in serial and in 2d problem.
Have you fixed this problem? If you have, can you tell me how did you achieve that?
I hope my poor English will not hinder you understanding my meaning.
Best wish!

I use foam-3.0-extend to simulate FSI, and I still encounter this error, can you help me?

Greetings wuwenbo and welcome to the forum!

Unfortunately you're not providing enough information in order to help you. Please read the following thread to understand what I mean: http://www.cfd-online.com/Forums/ope...-get-help.html

Because only in the second post you've made is there some inform about the exact error message. And that message seems to be due to the following reasons:

1. You're running in parallel, which can increase the complexity of the problem. Possible solution: First try to run in serial mode, to see if you get the same error.
2. The error message depends on what you're case is and what it looks like. More specifically, the error message suggests that the mesh is composed by very big cells and/or faces, for which the tolerance might not be applicable. For example, the message:
   
   Code:

   ---

   does  not match neighbour by 0.00287477 with tolerance 0.0001

   ---

   is telling you that the tolerance is 0.0001, which is the maximum allowed error. But the error you're getting is 0.00287477.

Therefore, as I've indicated above, please read this thread: http://www.cfd-online.com/Forums/ope...-get-help.html - and then follow the steps given there to provide enough information for people on the forum to be able to help you.

Best regards,
Bruno

Just a quick update for anyone exploring the tutorials with some recent findings between 2.3.x and extend3.1 versions. The floatingObject tutorial in 2.3 would be a better place to start. The tutorial in extend3.1 will have the object sinking, perhaps tuning the object properties will help but I would prefer 2.3's example which is really neat where the user can easily input the restrains and constrains.

foam extend 3.1 log at some time step:

Hi ,

I am facing the similar type of problem. I am trying to simulate a ship motion in OF2.3.x using waveDyMFoam (modified interDyMFoam). I have used displacementLaplacian solver for mesh motion (as in OF2.2.2) so that I can add more object. This solvers works fine for 2D and 3D box using wave at inlet. But when I am trying to use ship model, it is just sinking from first iteration and crash at the end. I am struggling with this problem for 2 weeks, still no success. I hope I will get some help from OF expert.

Ali

I just look this post and try the tutorial case.
I found out that there's decomposeParDict file in the system. (except I decide to parallel it into 4 part) That works just fine in my OpenFOAM 2.3.0

Dear All,

I need help with post processing of floatingObject tutorial.

Kindly can you please let me know, how to obtain the displacement of floatingObject in the x-direction (translation of the box in x-direction) with respect to time?

Thank you.
Gautami.

Quick answer: There was a tutorial in OpenFOAM 2.2.x that demonstrates this, it's the tutorial "mesh/moveDynamicMesh/simpleHarmonicMotion": https://github.com/OpenFOAM/OpenFOAM...HarmonicMotion

Gautami: did you do any postprocessing on the generated data? What do the data files look like?

Need help with changing the floating object to a .stl file cylinder
 

I have a question, can someone please help me out?
I want to run the solver multiPhase/interFoam/RAS/floatingObject but by default it runs with a cuboid body, I have a cylindrical body in .stl format and I want to use it as a floating object.
How can I do this? I have been able to insert the cylindrical mesh in blockMesh by using snappyHexMesh, but how can I use the cylinder as a floating object? Thanks if someone can help me out, I am doing a univerisity homework :)