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-   -   Mesh in Hexpress of Numeca (http://www.cfd-online.com/Forums/numeca/74258-mesh-hexpress-numeca.html)

jackr84 March 28, 2010 14:53

Mesh in Hexpress of Numeca
 
Hi, i must generate a mesh in Hexpress of Numeca, but I have some diffucult because it is the first time that I use Hexpress. I'm working with a geometry created with a scanner 3D. I can send also the geometry in PARASOLID.

Rombzh March 29, 2010 14:45

Well can you give more information about your case and your geometry ?
What kind of issues are you experiencing ?

The best to get used to Hexpress is to do the tutorials, which are quite simple and provide you with the basics.

jackr84 March 29, 2010 15:37

1 Attachment(s)
Hi, i send you an image of the geometry.I haven't experience in Hexpress because i always use Gambit, but for this case i must use hexpress. I must create a mesh.Can you send me some tutorials or can you gime me a help?i have the problems ti define the domain!!!If you want i can send the geometry in parasolid for email.

Rombzh March 29, 2010 16:24

Well first of all you might want to unite your three bodies. Then in the CAD menu, click on "export", you will be asked to define curves and surface resolution you want.
Once your domain is created you have to go through the steps that are shown in that picture :

http://www.numeca.be/uploads/pics/sp...m_small_01.gif

Initial Mesh generation
Adaptation to the geometry
Snapping to the geometry
Optimization
Viscous layer insertion.

It is very intuitive.

For tutorials you should check numeca's website.

jackr84 March 29, 2010 19:13

when i do the check of domain, the check in invalid. The domain is formed by vertex. How can i resolve this problem?

Rombzh March 29, 2010 19:54

I don't know, maybe you should decrease the size of the minimum captured vertex. Switch to the default values maybe.

Hamidzoka April 1, 2010 04:36

I think Rombzh is right.
you may solve this problem by reducing the size of minimum length captured. as a rough estimate, you can decrease the default value by divide it to 100.

jackr84 April 1, 2010 18:41

I don't resolve my problem! Can you help me? I can send the geometry in Parasolid. I'm working with this geometry in fluent but i have some problem to model the porous media. I want to use Numeca. I alway used Gambit to generate mesh. I have few days to di this.

Rombzh April 1, 2010 19:10

Can you provide us a screenshot of the input you prescribe when trying to export the domain ?
I am sorry I really do not have time to take a look at your geometry.

Maybe you simply should contact Numeca's tech support.

Hamidzoka April 2, 2010 06:54

can you export your parasolid model?
did you get a ".dom" file from parasolid model?
can you tell in which step of meshing you face with error?
i think you had better to explain us what you have done in HEXPRESS step by step.

jackr84 April 2, 2010 08:12

1 Attachment(s)
I import the file parasolid in Hexpress. My geometry is divided in three volume: inlet,porous media and outlet.
I first of all export the volume if inlet and work on the it. I merge the faces. The domain check is valid. Then i do the "initial mesh". The problem is "adapt the geoemtry", hexpress don't adapt the mesh to geometry.

Rombzh April 2, 2010 10:42

How have you defined your boundary conditions ?
In the adaptation menu, what are your inputs ?

When you say that the adaptation step is not done by Hexpress, what is actually happening ? Any error messages ?

jackr84 April 2, 2010 10:51

The boundary condition for the entire model are:
velocity inlet;
outflow;
wall;
Besides i insert inlet and outlet in the porous media.

In the adaption menu i don't insert nothing input.What do I insert?

Rombzh April 2, 2010 11:39

You need to specify the level of refinements you want for each wall boundary condition.

jackr84 April 2, 2010 11:44

I specified the level of refinement but the mesh don't adapt to the geometry.

Rombzh April 2, 2010 12:08

What does that mean ? you need to be more specific. Can you attach a picture of your adaptation menu, with the different boundary condition settings (level of refinement, target cell size, curvature, Aspect ratio) ?

jackr84 April 2, 2010 15:14

I don't knows values that i must set in the mirror!!!Help me

jackr84 April 2, 2010 15:15

1 Attachment(s)
Sorry the imeage is here

Hamidzoka April 2, 2010 23:41

dear jack;
"adapt the geometry" is probably the most time consuming part of meshing in this method. so you should be patient enough. the following tips concerning to your case come to my mind. please check them and report the ruslts:
1- when exporting the body to domain, in "faceting settings" reduce the "maximum length" value. you can ,as a rough estimate, devide its default value by 100.
2- increase the x,y,z initial meshes as much as possible. sometimes this error is due to improper size of elements. so try different elemet numbers in x,y and z directions.it may be time consuming.
3- check your solid model. maybe you have some discontinuities inside your model. or you may have some sharp faces or very low angles which do not allow the meshes to attach to your boundaries. Hex meshes are more sensitive than Tet meshes to sharp faces and low angles of geometries.
if you can mesh your model in Gambit, that may be because of Gambit Tet meshes which are more flexible. try to make your model a rather simpler if 1 and 2 tips does not help.
regards

jackr84 April 3, 2010 03:51

I want to make in hexpress because fluent don't resolve exactly the porous media. It's a diffult geometry for the first time that i use hexpress. Who do you help me to do mesh?My contact msn is: jackr84@hotmail.it


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