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-   -   Structured mesh and boundary layer with Salome (http://www.cfd-online.com/Forums/openfoam-meshing-open/90819-structured-mesh-boundary-layer-salome.html)

wwrfd July 21, 2011 10:25

Structured mesh and boundary layer with Salome
 
4 Attachment(s)
Hi everyone,

I'm supposed to make a study on cylindrical shapes using Salome openFOAM coupling.
Problem is I want to make a structured mesh with boundary layers on it. I saw some threads talking about that, but there weren't making any reference to my problem. I understood the process to refine the mesh near the BC walls (I attached some pictures) but my geometry is made of several cylinders crossing each others and I had to use the boolean operation "fuse" to have only one solid that make the fluid volume.

At the intersections of the cylinders, the algorithm of quadrangle mapping doesn't work because I don't have 4 edges (which is logical unfortunatly...) so I wondered if there were a way to project the faces or to do a sketch on the main cylinder (the horizontal one) of the others cylinders to have 4 edges per face instead of using the boolean operation fuse that creates meshing problem (for structured mesh).
I hope I explained it the right way so everybody can understand the problem.

I attached some pictures of my geometry and a structured mesh with a "pseudo" boundary layer I managed to create on a simple cylinder.

Thank you for your replies.

Attachment 8495

Attachment 8496

Attachment 8497

Attachment 8498

vasanthkch December 17, 2011 02:33

Quote:

Originally Posted by wwrfd (Post 316937)
Hi everyone,

I'm supposed to make a study on cylindrical shapes using Salome openFOAM coupling.
Problem is I want to make a structured mesh with boundary layers on it. I saw some threads talking about that, but there weren't making any reference to my problem. I understood the process to refine the mesh near the BC walls (I attached some pictures) but my geometry is made of several cylinders crossing each others and I had to use the boolean operation "fuse" to have only one solid that make the fluid volume.

At the intersections of the cylinders, the algorithm of quadrangle mapping doesn't work because I don't have 4 edges (which is logical unfortunatly...) so I wondered if there were a way to project the faces or to do a sketch on the main cylinder (the horizontal one) of the others cylinders to have 4 edges per face instead of using the boolean operation fuse that creates meshing problem (for structured mesh).
I hope I explained it the right way so everybody can understand the problem.

I attached some pictures of my geometry and a structured mesh with a "pseudo" boundary layer I managed to create on a simple cylinder.

Thank you for your replies.

Attachment 8495

Attachment 8496

Attachment 8497

Attachment 8498

hi,
i am doing flow inside a cylinder i have a question how did u mesh that cylinder can please help me im facing problem that is base for my project i am new to this openFoam

wwrfd December 21, 2011 06:46

Quote:

Originally Posted by vasanthkch (Post 336142)
hi,
i am doing flow inside a cylinder i have a question how did u mesh that cylinder can please help me im facing problem that is base for my project i am new to this openFoam

Hi, do you also use Salome to mesh the cylinder? Otherwise I would advice you to use Salome only to export the geometry in STL. file, so you can mesh it with SnappyHexMesh, there are excellent tutorials for meshing a cylinder with it, moreover, when I started my project the version 2.0 of openFOAM wasn't released yet, but the last update SnappyHexMesh has been improved and I think it will be perfect for your projet. You have several tutorials to use SnappyHexMesh, may I suggest you to refer to this one: http://openfoamfoorumi.com/wordpress...inenAaltoU.pdf
You can also refer to this thread for snappyHexmesh:
http://www.cfd-online.com/Forums/ope...ture-edge.html

If you really want to do the meshing part with salome, I can write you a small tutorial with screen captures to show you how to do it.

Good luck for your project.

Regards.

j-avdeev February 21, 2012 05:01

Quote:

Originally Posted by wwrfd (Post 336596)
If you really want to do the meshing part with salome, I can write you a small tutorial with screen captures to show you how to do it.

Can you made it or post a link to any information around this theme?
Thank you.

kid April 4, 2012 03:06

Hello Robin,
Need structured mesh for NACA0012 airfoil. Salome was used to create un-structured mesh, but for airfoil one required structured mesh for capturing boundary layer.

Can you guide me on how to generate structured mesh in Salome? (not snappyHexMesh)

Regards,
CFDkid

Maimouna September 4, 2014 09:48

[QUOTE=

If you really want to do the meshing part with salome, I can write you a small tutorial with screen captures to show you how to do it.

Good luck for your project.

Regards.[/QUOTE]

Dear Robin,

could you guide me please to mesh flow around circular cylinder using Salome. If you still have that tutorial with screen capture, it would be really grateful to help me please. Or any other tutorial could help me;).

Kind regards

wwrfd September 4, 2014 12:49

Tutorial
 
Hi,

Very old threat, I assume it's still difficult to generate a structured mesh even with the latest release of Salome? I haven't used it for almost 2 years but I remember how I did it ( I think).

For a cylinder shape it is very easy, you just define a circle split into as much vertices as you want as long as you define 4 edges per surface (to ensure strutured mesh). For this example I just designed a square, and then add vertices at a 45 deg angle and a fixed distance from the center of the square. From that I generated 5 surfaces, used the merging operation (boolean operation) put the same number of elements on vertices to ensure a structured mesh (bijection). Once you get that, you extrud your mesh in one of the axis of your cylinder.

I may check that if I have time to play with it to see what it is, but they made really good improvement so far compared to when I used to use it. I'll upload a short presentation that explains the step that I did at that time. For any complex shapes, I don't really recommend salome if you're doing CFD analysis and need a structured mesh, have you tried Gmsh?

Kind regards.

Robin

Maimouna September 5, 2014 06:31

Dear Robin,

lots of thanks for your help. I just installed Salome yesterday, I'm still not familiar with it. :confused:

If you could try and do the small presentation for that, it would be really grateful.:)

I myself would like to use Gmesh, but I'm still learning it. If you have such tutorials would help me, I would be really grateful.;)

Best regards

Maimouna


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