[jack2000]

Dear all,
I am a brand new OpenFoam user. I have some difficulties to understand how fill the boundary information. For example, in the case of icoFoam of tutorials, what is real meaning of nFaces and startFace? How can get information from a mesh? I would very appreciate if somebody can give me an answer.

Regards!

Jack


PS: part of boundary information from the icoFoam tutorials.

movingWall
{
type wall;
physicalType wall;
nFaces 20;
startFace 760;
}

fixedWalls
{
type wall;
physicalType wall;
nFaces 60;
startFace 780;
}

frontAndBack
{
type empty;
physicalType empty;
nFaces 800;
startFace 840;
}

[gschaider]

That information is found in the Userguide Section 6.1.2

But don't bother about these numbers. Nobody (I guess not even Henry, Hrv or Mattijs) edits them by hand. You let utilities do that for you.

[jack2000]

Hi, Bernhard,
Thank you very much for giving me some suggestion. Could you tell me what untilies I can use for finding nFaces and startFace if I have already generated a mesh? Could you use icoFoam as the example to show me how to use it? I will very appricate for that.

Best Reagrds!

Jack

[gschaider]

Jack.

The utilities I was refering to are mesh generators like blockMesh and manipulators like splitMesh. They write these values and there is no need to touch them in a solver like icoFoam.

If you are a brand new user there are two things you have to know about them:

- Their meaning is explained in section 6.1.2
- Don't touch them (you'll propably break the mesh)

[jack2000]

Hi, Bernhard,
I am very appreciated for your help.
Based on your answer and the testing, I am now clear that the boundary file is generated by blockMesh.

Because my FoamX doesn't work, I try to prepare the mesh and other input data manually without using FoamX. Do you think this idea works? Thank you very much again!

Best Regards!

Jack

[giovanni]

Hi Jack,

I had the same problem, but i discovered that the boundary file is generated automatically by the command blockMesh. So you haven't to define nFaces and startFaces.

If you want to understand better what they mean, try to generate one simple block: hex (0 1 2 3 4 5 6 7) (1 1 1) simpleGrading (1 1 1), then divide it in two parts (1 2 1), finally in 8 parts (2 2 1).

It will be easier to understand face's numbers and their location.

Good Luck

Giovanni