[Gmsh] Problem meshing a sphere. gmsh crash meshing or not recognize the volume.

[Hugo Fernando Maia Milan]

Hi Esteban,

Ok. In this case, you need to comment lines 38 and 39 of the code. With that, the surface of the sphere will be draw, but it will not be considered as a volume. So, you will get an box with a hole with the shape of a sphere, as you desire.

What do you mean by corrupted? Aren't you achieving the mesh yet? If this is the case, change the parameters of the point size. If you increase them, the elements will be larger and it is likely that you will get a mesh.

In respect of the problem that you are facing in the Ubuntu, I've got no idea how to fix it. May be if you uninstall it and install the new version it could work. You could also try to compile the source code directly. However, before trying to reinstall, try this to generate the mesh: gmsh name_of_input_file.geo -3 -optimize -o name_of_output_file.msh

If you get in troubles, set the output of the gmsh with that command.

Hugo

Date: Wed, 24 Sep 2014 23:08:00 -0500
Subject: Re: [Gmsh] Problem meshing a sphere. gmsh crash meshing or not recognize the volume.
From: vb.esteban at gmail.com
To: hugomaiamilan at hotmail.com; gmsh-request at geuz.org; gmsh at geuz.org

Hi Hugo.
Well, what I'm trying to find is something like the file attached, where the flow goes around an element. Is what your code do too? If you note, the submarine volume is empty, and the all mesh is located around the submarine. 
The gmsh file of that case is corrupted so it's impossible to see, that's the reason what I'm confuse.
Thanks for the patient and the answers.
Best regards, and thankyou again!
2014-09-24 7:00 GMT-05:00 Hugo Fernando Maia Milan <hugomaiamilan at hotmail.com>:



Hi,

I didn't unterstand your question. What do you mean by "volume of the sphere without mesh"? If you are simply using my code, you can get the volume by the radius in the file. As you can see in the code, "raio" is the radius of the sphere.

Hugo

Date: Tue, 23 Sep 2014 23:32:43 -0500
Subject: Re: [Gmsh] Problem meshing a sphere. gmsh crash meshing or not recognize the volume.
From: vb.esteban at gmail.com
To: hugomaiamilan at hotmail.com
CC: gmsh-request at geuz.org; gmsh at geuz.org

Thanks hugo. 
That works nice and finally can get the mesh.
But, how do I proceed to get the volume of the sphere with no mesh? It's possible? 
2014-09-23 8:00 GMT-05:00 Hugo Fernando Maia Milan <hugomaiamilan at hotmail.com>:



Hi,

It looks that the size of the point that you defined are very small compared to the size of the object. I had created a new file, check it in the attached.

In this file, you can specify the radius of the sphere and the lengths of the rectangle. Pay attention in the size of the points because they are critical in regard of the size of your elements (and the mesh, consequently).

If it is too slow or you can't create the mesh, just increase the values of lc and lesfera in the file.

Hugo.

Date: Mon, 22 Sep 2014 10:28:20 -0500
From: vb.esteban at gmail.com
To: gmsh-request at geuz.org; gmsh at geuz.org
Subject: [Gmsh] Problem meshing a sphere. gmsh crash meshing or not	recognize the volume.

Hi.

I'm a new user of gmsh, I have developed some tutorials in it, but now i have several problemas.

I'm trying to simulate the flow around a sphere, the main goal is calculate the drag force and drag coefficient in OpenFOAM. However, I'm having a lot of problems creating the mesh, I've made two process to generate the mesh with no success at all.

First way.
1. I generate a CAD model in solidEDGE, in that model I draw a solid volume with the hole of the sphere (boolean operation). The volume represent the all fluid.
2. I export the CAD Model into step, stl and igs files.
3. In gmsh, merge the step model.
4. gmsh show the surfaces, points and volumes rigth (gmsh show the walls in gray solid color).
5. Define the physical groups, surfaces with no problem.
6. When I try to select the volume in physical group is just impossible.

Second Way
As the geometry is a bit simple, I decided to draw the sphere and the box in which its embeded in gmsh.

1. I draw some points to define the sphere.
2. Create circle arc to define the sphere.
3. With those circle arcs created I defined ruled surface in the sphere.
4. Then Create the box around the sphere.
5. The surfaces in physical groups are defined normally, but I created a surface call sphere, in which I select the all ruled surfaces created on the sphere.
6. Select the volume in the physical groups (WHEN I DEFINED THE PHYSICAL GROUPS I'VE ALREADY DEFINED THE VOLUME AND SURFACES IN ELEMENTARY ENTITIES)
7. Then, with everything O.K. I try to create the mesh, but the program just crash, and close.

I have a problem to open gmsh to, everytime I try to open it I have to write in the console (Ubuntu) this: gmsh primary.geo -tol 1e-9

I attach the geo file.

Thanks! I really appreciate any comment about it.

spheredesarrollada.geo is the second way file generated.
sphereNueva.geo is the first way file
-- 
Esteban Vargas BolívarMetálicas Léguz S.A.Tel.: (4)5203600 Ext. 103


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-- 
Esteban Vargas BolívarMetálicas Léguz S.A.Tel.: (4)5203600 Ext. 103
 		 	   		  


-- 
Esteban Vargas BolívarMetálicas Léguz S.A.Tel.: (4)5203600 Ext. 103
 		 	   		  
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