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 Silvy October 27, 2013 08:19

Problem with mesh generation

Dear all ,
I am very inexperienced in OpenFOAM ,so I apologize if my question is too trivial.
I have a problem with the generation of my mesh. Using blockMeshDict I ​​have created a box with inside a cylinder. I set the boundary conditions (inlet , outlet , simmetry , AMIinside and AMIoutside ) .
By snappyHexMeshDict then I put in the cylinder the stl geometry of a turbine .
But when I run snappyHexMesh in ParaView I can only see one geometry, or the cylinder with the turbine on the inside, or the box without the cylinder inside of it .
I can see only one or the cylinder or box depending on the point I took in locationInMesh. If I take a point out of the cylinder in ParaView I will only see the box without the cylinder. if I take a point inside the cylinder in ParaView I will see only the cylinder with the mesh of the turbine on the inside.
it seems that the two geometries are not linked . But if I build a single geometry so that the box and the cylinder have coincident vertices, I can no longer difinite AMI between the two geometries .
I also took a look at the tutorials as propeller and questions in the forum but I can not find a solution to my problem : connect the two geometries in blockMesh keeping the AMI as a boundary condition between the two .

Below is my file blockMeshDict.
Thank you very much for your help.

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.1.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 1;

vertices
(
(-10 11 -10) //0
(10 11 -10) //1
(10 11 10) //2
(-10 11 10) //3
(-10 -11 -10) //4
(10 -11 -10) //5
(10 -11 10) //6
(-10 -11 10) //7
(-17.6776695296636881100211 11 -17.6776695296636881100211) //8
(17.6776695296636881100211 11 -17.6776695296636881100211) //9
(17.6776695296636881100211 11 17.6776695296636881100211) //10
(-17.6776695296636881100211 11 17.6776695296636881100211) //11
(-17.6776695296636881100211 -11 -17.6776695296636881100211) //12
(17.6776695296636881100211 -11 -17.6776695296636881100211) //13
(17.6776695296636881100211 -11 17.6776695296636881100211) //14
(-17.6776695296636881100211 -11 17.6776695296636881100211) //15

(-17.6776695296636881100211 11 -17.6776695296636881100211) //16
(17.6776695296636881100211 11 -17.6776695296636881100211) //17
(17.6776695296636881100211 11 17.6776695296636881100211) //18
(-17.6776695296636881100211 11 17.6776695296636881100211) //19
(-17.6776695296636881100211 -11 -17.6776695296636881100211) //20
(17.6776695296636881100211 -11 -17.6776695296636881100211) //21
(17.6776695296636881100211 -11 17.6776695296636881100211) //22
(-17.6776695296636881100211 -11 17.6776695296636881100211) //23
(-75 11 -75) //24
(75 11 -75) //25
(75 11 75) //26
(-75 11 75) //27
(-75 -11 -75) //28
(75 -11 -75) //29
(75 -11 75) //30
(-75 -11 75) //31

);

blocks
(
hex (0 1 2 3 4 5 6 7) rotor (10 10 10) simpleGrading (1 1 1)
hex (8 9 1 0 12 13 5 4) rotor (10 10 10) simpleGrading (1 1 1)
hex (1 9 10 2 5 13 14 6) rotor (10 10 10) simpleGrading (1 1 1)
hex (10 11 3 2 14 15 7 6) rotor (10 10 10) simpleGrading (1 1 1)
hex (0 3 11 8 4 7 15 12) rotor (10 10 10) simpleGrading (1 1 1)
hex (24 25 17 16 28 29 21 20) Fluid (10 10 10) simpleGrading (1 1 1)
hex (17 25 26 18 21 29 30 22) Fluid (10 10 10) simpleGrading (1 1 1)
hex (26 27 19 18 30 31 23 22) Fluid (10 10 10) simpleGrading (1 1 1)
hex (16 19 27 24 20 23 31 28) Fluid (10 10 10) simpleGrading (1 1 1)

);

edges
(
arc 9 10 (-17.6776695296636881100211 11 17.6776695296636881100211)
arc 13 14 (-17.6776695296636881100211 -11 17.6776695296636881100211)
arc 11 8 (17.6776695296636881100211 11 -17.6776695296636881100211)
arc 15 12 (17.6776695296636881100211 -11 -17.6776695296636881100211)
arc 9 8 (-17.6776695296636881100211 11 17.6776695296636881100211)
arc 13 12 (-17.6776695296636881100211 -11 17.6776695296636881100211)
arc 11 10 (17.6776695296636881100211 11 -17.6776695296636881100211)
arc 15 14 (17.6776695296636881100211 -11 -17.6776695296636881100211)
arc 17 18 (-17.6776695296636881100211 11 17.6776695296636881100211)
arc 21 22 (-17.6776695296636881100211 -11 17.6776695296636881100211)
arc 19 16 (17.6776695296636881100211 11 -17.6776695296636881100211)
arc 23 20 (17.6776695296636881100211 -11 -17.6776695296636881100211)
arc 17 16 (-17.6776695296636881100211 11 17.6776695296636881100211)
arc 21 20 (-17.6776695296636881100211 -11 17.6776695296636881100211)
arc 19 18 (17.6776695296636881100211 11 -17.6776695296636881100211)
arc 23 22 (17.6776695296636881100211 -11 -17.6776695296636881100211)
);

boundary
(
inlet
{
type patch;
faces
(
(27 24 28 31)
);
}
outlet
{
type patch;
faces
(
(26 25 29 30)
);
}
symmetry
{
type symmetryPlane;
faces
(
(0 1 2 3)
(1 9 10 2)
(11 10 2 3)
(8 9 1 0)
(0 3 11 8)
(4 5 6 7)
(5 13 14 6)
(15 14 6 7)
(12 13 5 4)
(4 7 15 12)

(17 25 26 18)
(21 29 30 22)
(26 27 19 18)
(30 31 23 22)
(24 25 17 16)
(28 29 21 20)
(16 19 27 24)
(20 23 31 28)
(27 26 30 31)
(24 25 29 28)
);
}

AMIinside
{
type cyclicAMI;
neighbourPatch AMIoutside;
faces
(
(9 13 14 10)
(11 10 14 15)
(11 8 12 15)
(8 9 13 12)
);
}

AMIoutside
{
type cyclicAMI;
neighbourPatch AMIinside;
faces
(
(17 21 22 18)
(19 18 22 23)
(19 16 20 23)
(16 17 21 20)

);
}

);

 Lisandro Maders March 28, 2015 01:33

have you sorted your issue?

Hi,

have you sorted your issue? I am a beginner too, and I have a simple question that I hope you can answer, as I see since 2013 you use OpenFOAM.

I want to see my mesh on ParaView having only the blockMeshDict files as well the files generated by blockMesh command (points, faces, etc..). I do not have at the moment the solution files like fvSchemes, fvSolution, controlDict, etc.

Thanks a lot.

Regards, Lisandro

 alexB March 28, 2015 07:33

Hi Lisandro,

you can copy the necessary files from tutorial cases...
Just adapt them for your case afterwards.

regards
Alex

 Lisandro Maders March 31, 2015 19:29

Quote:
 Originally Posted by alexB (Post 538672) Hi Lisandro, you can copy the necessary files from tutorial cases... Just adapt them for your case afterwards. regards Alex
Yes but the thing is, I would need to adjust all the patches of the other case files to match ith the patches of my mesh.... If I need to do this everytime I want to create a mesh and verify it, it loses all the sense of creating the mesh and check it in the beginning..

Lisandro

 alexB April 1, 2015 16:03

you just need the controldict, fvSchemes and fvSolution files for blockmesh.
You don't have to run the solver. ;)

they are without any references to patches in the tutorial cases i saw.

regards Alex

 Gizazu June 10, 2015 08:59

Problem with mesh generation

2 Attachment(s)
Hi. Iḿ new to OpenFoam, and i hope i can find support here with your help.

I´m trying to create a channel with a pier inside of it, I want the pier to be an obstacle. I wrote the blockMeshDict and then when i was running blockmesh, an error returned (see image)

Attached there is the blockMeshDict file.

Help me please, i want to know what i did wrong? or what is missing?

Regards

 alexB June 10, 2015 17:49

Hi Gizela,

after starring a while at your blockmeshdict, I solved your problem.

You made one error in reasoning... If you want to simulate the flow around an obstacle, you haven't to mesh the obstacle itself.

Just remove your last block and look at your mesh with paraView etc.

You will realize your error. ;)

regards
Alex

 Gizazu June 11, 2015 04:49

Quote:
 Originally Posted by alexB (Post 549891) Hi Gizela, after starring a while at your blockmeshdict, I solved your problem. You made one error in reasoning... If you want to simulate the flow around an obstacle, you haven't to mesh the obstacle itself. Just remove your last block and look at your mesh with paraView etc. You will realize your error. ;) regards Alex
Hi Alex,

Thank you, it worked and i already have my channel with a pier.

I have a doubt:
The scope of my thesis is to study the development of the cavity of erosion around the pier.
Now that i have the channel mesh, i want to know what solver can I use to simulate that and how can I represent and consider sediment transportation in OpenFoam?

Is it right to use the pisoFoam solver to study the pressure and velocity around the pier (taking the bed as a dynamic/moving wall - to analyze the bed deformation)?

Regards
Gizela

 alexB June 11, 2015 16:45

Hi Gizela,

I am glad that it was just this little prob with your mesh.

And I must say, that I am not into your other issue.

But one suggestion:
Better post in another subforum (solvers etc. ), there you will get quick better help.

regards
Alex

 Gizazu June 12, 2015 08:11

Thank you Alex.

I´ḿ going to do that.

Regards

 sohrabmajd July 12, 2015 04:05

propller domain meshing with ansys meshing

hi 2 all
I'm new user of ansys that want to use ansys cfx for a ducted propeller.
i can't mesh my model as good as that my solver give me best results.
how can i mesh my model with boundary layers that have fine meshes near propeller and duct and meshes grow slowly linearly with distance from the duct?
I work with ansys workbench and fluid flow(CFX).
thanks:(

 Lisandro Maders July 12, 2015 06:36

Quote:
 Originally Posted by alexB (Post 539525) you just need the controldict, fvSchemes and fvSolution files for blockmesh. You don't have to run the solver. ;) they are without any references to patches in the tutorial cases i saw. regards Alex

I forgot to give you a feedback. I was missing the fv* files.. Once I put them in their respective folders I could see it! Thank you!

Lisandro

 alexB July 12, 2015 16:10

Quote:
 Originally Posted by sohrabmajd (Post 555063) hi 2 all I'm new user of ansys that want to use ansys cfx for a ducted propeller. i can't mesh my model as good as that my solver give me best results. how can i mesh my model with boundary layers that have fine meshes near propeller and duct and meshes grow slowly linearly with distance from the duct? I work with ansys workbench and fluid flow(CFX). thanks:(
wrong subforum ;) you are in the OpenFOAM-subforum... with OpenFOAM I would recommend snappyHexMesh to you. ;)

regards
Alex

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