[hchen]

Hi Pablo:

Do you have plans to code volume averaged turbulence models for flow in porous media? If so, what kinds of VA turbulence model would you like to choose?

Best regards
Hao

[Phicau]

Hi Hao,

the VA turbulence models, k-epsilon and k-omega SST, are already developed and almost ready to be released, I just need a little time for code cosmetics and to port them to all the supported versions.

I am now finishing writing my PhD and don't have as much time as I would want to develop IHFOAM, but I think you can expect them in the following 3 weeks, along with a tutorial case to apply them.

Best,

Pablo

[hchen]

Hi Pablo:

Thanks very much for your work and I am looking forward to the new released version!

Do you have any comments on the applicability range of these two turbulence models based on your practical experience? e.g. under what kind of conditions k-epson gives better results and so on...

Best regards
Hao

[Phicau]

Hi Hao,

you have a thorough comparison here (if you don't have access just let me know by PM): http://www.sciencedirect.com/science...78383912001093

Most of the times the results are very similar, although I think SST stands out when wave breaking or large flow separation occurs.

Best,

Pablo

[hchen]

Hi Pablo:

Thanks very much for your info. I have access to it and I am reading it thoroughly.

Could you give some refs on the VA turbulence models that IHFOAM follow?

Best regards
Hao

Originally Posted by Phicau

Hi Hao,

you have a thorough comparison here (if you don't have access just let me know by PM): http://www.sciencedirect.com/science...78383912001093

Most of the times the results are very similar, although I think SST stands out when wave breaking or large flow separation occurs.

Best,

Pablo

[Phicau]

Hi Hao,

sure, check this reference: http://www.sciencedirect.com/science...78383913001452

As it happens with our VARANS equations, the turbulence equations are not 100% mathematically correct. However, we have only encountered minor differences with the new derivation/implementation.

We are exploring the possibility of publishing the new material. In any case, the new equations will be included in the reference document that you can download when you register in the IHFOAM website.

Best,

Pablo

[haze_1986]

Hi all, I would just hope to ask for advice on the mesh resolution of VoF in ihFoam. Validating of experimental results seems to give me good results when the total length of the flume are around 20 to 50 metres. I would normally use horizontal mesh spacing of 0.1 metres and 0.05 metres vertically.

However, in the case of real simulations of lets say a harbour that can be 500 metres in the area of interest, what would be the recommended mesh resolutions? I am not sure from which physical quantity should I start with to predict. Would the resolution be dependent on the inlet boundary wave length as well?

[Phicau]

Hi Haze,

yes, you usually need a certain number of cells to accurately define a wave. In general you should go for at least 5 cells per H and 75 cells per L.

Best,

Pablo

[haze_1986]

Originally Posted by Phicau

Hi Haze,

yes, you usually need a certain number of cells to accurately define a wave. In general you should go for at least 5 cells per H and 75 cells per L.

Best,

Pablo

Hi Pablo,

Happy New year and thanks for the advise. I would just like to check if there is also a strict requirement that the aspect ratio of each cell be less than 2? What can we do if after applying the above the aspect ratio H:V we obtain is about 10? Any issues with it?

[Phicau]

Hi Haze,

in CFD there are very few strict requirements. In this case it is a recommendation. Having said that, I would never go beyond 5:1 (and this at an unimportant location far from the interest zone, though).

Best,

Pablo

[haze_1986]

Hi all, I came across a problem which I am not able to solve. I am trying to test a diffraction of waves case which is fully 3D. I sampled the surface elevation at the inlet and the trend is different from the Stokes wave I generated in IHFoam. Does anyone knows why and if there is anything I can do to improve the solution?

[rafa13]

Hi Pablo,

First, I want to thank you for your great tool box e that you are "putting" it in open-source!!

I have a issue with IHFoam when i try to import a mesh ,created in Gmsh, so i try to explain it a little bit more...

I can import using gmshToFoam and I don get error...but when I execute the checkMesh I get this error message:

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time



--> FOAM FATAL ERROR:
No times selected

From function checkMesh
in file db/Time/timeSelector.C at line 263.

FOAM exiting


I run the case without the blockMesh command in the runCase file and it runs, but i don't know why i have this checkMesh issue...
...can you help me with this problem? by the way I use OpenFoam 2.2.2

Thanks a lot,
Rafael Marques

[Phicau]

Hi Rafael,

you give little information, there a lots of things that can go wrong. For example: are you running the command in the base folder of a case? Do you have a folder named '0' (even empty)? Do you have any folders with an space in their name inside the case folder (I think that would yield another kind of error, though)?...

Best,

Pablo

[rafa13]

Hi Pablo,

thanks for your time and for the quick answer.

Ok I try to explain the steps that I do:
first I copied the basewaveflume tutorial and rename it. After that I copy my Mesh file in to the case folder, then I delete the PolyMesh folder in the constant folder after that I run the command gmshToFoam in the command window and this comand are able to create the Polymesh folder thats not the problem, and then I change the boundary file ( changing the frontAndback patch to empty) and at the end i run the checkMesh in the command window again. Thats the moment when I get this error message, but I delete the blockMesh command in the ControlDict and I am able to run the case with the ./runCase file.

So I get results, but I like to checkMesh...but never mind the important thing are the results so they are Ok so everything is fine.

I decided to check the mesh in a OpenFoam case and it works without problems-

thank you again
Rafael

[Phicau]

Hi Rafael,

then I was right, you need to create a folder named '0' for checkMesh to work. Note that there is only a folder named '0.org' that eventually gets renamed to '0' in the runCase script.

Best,

Pablo

[rafa13]

Hi Pablo

Thanks a lot it works, i am a noob using OpenFoam sorry about this noob issue.

greetings

Rafael

[rafa13]

Hi Pablo,

I am struggling with the distribution of the gauges, for the free surface elevation. I am trying to make a equal spaced distribution of 200 gauges, a little bit like the waveflume tutorial in waves2foam. But i am not able to do it, so I decide to ask you about it.

I am able to monitorize the surface elevation at various positions, like the breakwater tutorial, but now I want to monitorize at 200 positions and introducing every position by hand is at the moment my only way.

Greetings,

Rafael

[Phicau]

Hi Rafael,

you can create your own script to generate a text block that includes all the points you need to sample, so that you can include it in sampleDict.

After that the script (postSensVOF.py) provided as part of the reference materials will do the rest.

Best,

Pablo

[rafa13]

Hi Pablo,

thanks for your answer, I tried it but without success at the moment, but I continuo to try. Thats the nice thing about OpenFoam try and try till it works .

Best greetings,

Rafael

[hchen]

Hi Pablo:

In your tutorial for boundary conditions of p_rgh for solid walls, you use buoyant pressure rather than zero gradient, could you explain the reason?

Best regards
Hao