[eruwaedhiel]

Hello everyone! I'm Liz, and I am very new to OpenFOAM, so please excuse me if I made a very obvious mistake. I am working on a project that requires me to model the approximate flow from a helicopter. I am using the pimpleDyMFoam tutorial "propeller" as a model, as I need to get the helicopter rotors rotating above the static fuselage. I have .obj and .stl files for all my model components and have run snappyHexMesh several times successfully. However, all I can ever see in paraFoam is the original mesh from blockMesh.

I know this question has come up several times on the forum but the solutions proposed there have not resolved my problem. I've tried moving the locationInMesh point around, running with and without -overwrite, and switching from .obj files to .stl files (this gave me an error with snappyHexMesh saying stl was not an accepted file type - I'm still confused by this since I have made a mesh with an stl before...).

I've attached all the relevent dictionaries and the snappyHexMesh log, I'd really appreciate it if someone could take a look and point out anything that looks wrong. I'm still learning how everything works together and probably have several mistakes besides whatever is causing this problem.

Thanks!

[eruwaedhiel]

My models were too large to post initially, but I checked them into a bitbucket repo, so if they would be helpful you can get them by cloning the repo with "git clone https://eruwaedhiel@bitbucket.org/eruwaedhiel/cfd_models.git" or just going to https://bitbucket.org/eruwaedhiel/cfd_models/downloads and downloading it.

[alexB]

Hi,

I am not very experienced myself, but I have got two ideas.

1) do you have ASCII stl fiels? Perhaps it goes wrong because you used binary stl files.

2) have you tried to look at different timesteps with paraFoam?
At my beginning I had an similar "error" ... I used sHM with an option to write the mesh at different stages. I could look at them with paraFoam on different timestages.

regards
Alex

[eruwaedhiel]

alexB,

Thanks for the suggestions! Currently the stl files are not working at all for me - I had to convert to .obj files otherwise snappyHexMesh gives me a "not an accepted file type" error. What's strange is that I have made a mesh from the same stl files a few days ago, but it doesn't seem to work in this version based on the propeller tutorial. Maybe stl files can't be used for dynamic meshes?

I have tried looking at different time stamps in paraFoam and still see nothing. When I use the -overwrite flag, time 0 is the only option, but when I tried without that flag, I scrolled all the way to the last time stamp and still saw only an empty box

[alexB]

Hi,

I think the best would be to post the full error message, the snappyhexmeshdict and the surfacefeatureextractdict. Perhaps we can locate the error with that files.

regards
Alex

[eruwaedhiel]

Hi Alex,

I have attached the output I get using the the .obj files showing I don't get an error when I use them in my original post. The zip file I attached also should have all the dictionary files I used. I'll make sure everything you need is actually there when I get back on my computer (I'm just on my phone right now). Thanks!

[alexB]

Hi,

I just took a short look, but I noticed that you refer to different files in snappyHexMeshDict and surfaceFeatureExtractDict.

I hope it's the only error.

Otherwise I think you have to check your geometry *, even if it worked before. (or you can reproduce your working case)

* I don't know how it works, but I think a utility called checkSurface (or similar) should show an error if something is wrong.

regards
Alex

[eruwaedhiel]

Alex,

Thanks, I will definitely check that out once I'm home tonight! I probably missed some parts changing over names from the propeller tutorial to my helicopter case. What exactly is the surfaceFeatureExtractDict for anyway?

Liz

[eruwaedhiel]

Hmm, looks like its still not working. I did notice that the Allrun.pre script I've been trying fails when it goes to run surfaceFeatureExtract, but I'm not sure how essential that step is.

[alexB]

Hi Liz,

at first which version of OF are you using? (I have missed to ask that )

The surfaceFeatureExtract step looks for edges in your geometry files, so sHM can snap to them in the snapping step.

I haven't done much with sHM but for the surfaceFeatureExtract step I have used the extractFromSurface method, like in this tutorial http://www.calumdouglas.ch/openfoam-...snappyhexmesh/ from the youtube video https://www.youtube.com/watch?v=ObsFQUiVi1U .

You can download the surfaceFeatureExtractdict fro the homepage if you want.

regards
Alex

[eruwaedhiel]

I'm using OpenFOAM-2.3.1.