[tareqkh]

Hello Foamers,

I have used gmsh to mesh different 2d cases such as airfoil, cylinder, backward facing step, C-D nozzle,..etc. The procedure was to create a 2d model and extrude it. However, if we had models like a full car body or a 3d airfoil and wanted to mesh it, how would we handle a full 3d models in gmsh. I did some research on google hoping to find some examples, but there were not enough explanation in this topic. Has anyone of you done some 3d problems on gmsh and find some time to help in this topic...

Thank in advance,

[Maimouna]

Dear Kamalj,

have you found your question answer, I'm actually looking for the same question? If yes, share me your experience please.

Best regards

Maimouna

[tareqkh]

Dear Maimouna,

Thank you for your kind reply. I am still working on finding such cases on the internet. I have found this tutorial attached in this link https://albertsk.files.wordpress.com...h_tutorial.pdf, but unfortunately it might not be as you would expect.

In the meantime, I have switched to snappyhex mesh and found it really helpful. I can help you if you want to make a mesh.

Regards,

Tariq

[Maimouna]

Dear Tareq,

Many thanke for your very kind reply as well. Sure I need your help in snappyHexMesh, I never used it. My case is shown in the attached picture. I tried both blockMesh and Gmsh, but unfortunately, none of them work for me till now.

Beam thickness is 0.06 cm. I hope I could solve my meshing problem using snappy. For any shearing files my email is: may78may@hotmail.com.

Lots of thanks in advanced.

Maimouna

[tareqkh]

Dear Maimouna,

Can you please send me the original document of the example that you just showed me?

Regards,

Tariq

[Maimouna]

Dear Tariq,

the example is in the paper titled ''Strong coupling schemes for interaction of thin-walled structures and incompressible flows'', sorry, I have attachment problem in order to its size I couldn't attach you the paper.

For any question, I'm ready to answer.

Best regards

Maimouna

[opedrofunk]

Hi,
Gmsh is a great tool. However, if you want to use it in a production environment then you'll need an efficient way to create/modify/clean/import/export geometry in to Gmsh's native format (*.geo).

I use SketchUp (free) and the SketchUp MeshKit plugin (also free) to do this: http://extensions.sketchup.com/en/co...y-tetgen-tools

The Sketchup/Meshkit/Gmsh stack is awesome for working efficiently with OpenFOAM for professional work.

Enjoy!
Peter

[Maimouna]

Dear Peter,

many thanks for your post. I already made geo file for my case as its shown below

cl1 = 0.5;
cl2 = 0.2;

Point(1) = {0, 0, 0, cl1};

Point(2) = {20, 0, 0, cl1};
// 
Point(3) = {0, 11, 0, cl1};

Point(4) = {20, 11, 0, cl1};

Point(11) = {0, 0, 11, cl1};
Point(12) = {20, 0, 11, cl1};
Point(13) = {0, 11, 11, cl1};
Point(14) = {20, 11, 11, cl1};

Line(1) = {1, 11};
Line(2) = {11, 12};
Line(3) = {12, 2};
Line(4) = {2, 1};
Line(5) = {13, 14};
Line(6) = {14, 4};
Line(7) = {4, 3};
Line(8) = {3, 13};
Line(9) = {11, 13};
Line(10) = {12, 14};
Line(11) = {2, 4};
Line(12) = {1, 3};
Line Loop(13) = {1, 2, 3, 4};
Plane Surface(14) = {13};
Line Loop(15) = {8, 5, 6, 7};
Plane Surface(16) = {15};
Line Loop(17) = {1, 9, -8, -12};
Plane Surface(18) = {17};
Line Loop(19) = {3, 11, -6, -10};
Plane Surface(20) = {19};
Line Loop(21) = {2, 10, -5, -9};
Plane Surface(22) = {21};
Line Loop(23) = {4, 12, -7, -11};
Plane Surface(24) = {23};

Point(101) = {5, 5, 4, cl2};
Point(102) = {6, 5, 4, cl2};
//thickness of plate is 0.1
Point(103) = {6, 5+0.45, 4, cl2};
Point(104) = {6, 5+0.55, 4, cl2};
Point(105) = {6, 6, 4, cl2};
Point(106) = {5, 6, 4, cl2};
For i In {1:5}
    Line(100+i) = {100+i, 100+i+1};
EndFor
Line(106) = {106, 101};
Line Loop(111) = {101, 102, 103, 104, 105, 106};
Plane Surface(111) = {111};

Point(113) = {6+4, 5+0.45, 4, cl2};
Point(114) = {6+4, 5+0.55, 4, cl2};
Line(113) = {103, 113};
Line(114) = {104, 114};
Line(115) = {113, 114};
Line Loop(116) = {103, 114, -115, -113};
Plane Surface(117) = {116};
vo1[]={Extrude {0, 0, 3} {Surface{111, 117};} };

Surface Loop(172) = {18, 14, 22, 20, 24, 16};
Surface Loop(173) = {170, 117, 162, 166, 171, 148, 111, 128, 132, 149, 140, 144};
Volume(174) = {172, 173};

Physical Surface("inlet") = {18};
Physical Surface("outlet") = {20};
Physical Surface("top") = {16};
Physical Surface("bottom") = {14};
Physical Surface("front") = {22};
Physical Surface("back") = {24};
Physical Surface("cylinder") = {128, 148, 111, 149, 144, 132};
Physical Surface("interface") = {166, 140, 117, 162, 170, 171}; 
Physical Volume("mesh") = {174};

Coherence;

Could you please explain me step by step what to do next till compiling the solver in OpenFOAM? I never used sketchUp nor MeshKit. I hope that would help because I have been stuck on my case from more than 2 months.

Many thanks in advanced.

Maimouna

[opedrofunk]

Hi,
Sure. The basic process is:
1) Import or Draw your geometry in SketchUp. Use the MeshKit SketchUp plugin to set boundary names, region names, desired mesh refinement etc. and then export to Gmsh format (*.geo file).
2) Use Gmsh to mesh your *.geo file. You'll then have a *.msh file which has your mesh.
3) Use the included gmshToFoam utility to convert your *.msh file in to the native OpenFOAM mesh format (i.e. $ gmshToFoam /path/to/your/mesh.msh). All boundaries will be imported as type "patch", so if you have some "wall" types, just use a changeDictionaryDict to set that (tons of examples in the tutorials - have a look at the chtMultiRegionFoam tutorial to see that in action).
4) Done! Just set up the boundary conditions for your case like normal!

I hope that helps!
Peter


P.S. Once you have a quality tet mesh in OpenFOAM format you can play around with the polyDualMesh utility... it's what all the kids are in to these days :-)