[Gmsh] higher order mesh from Gmsh doesn't works--gmshToFoam

hewei · February 6, 2015, 05:57

Hi all,

I found the utility gmshToFoam only works for first-order mesh, is it true?
the second-order mesh will not convert to OpenFOAM successfully, so does anybody know how to convert the higher order mesh? thanks.

alexeym · February 6, 2015, 07:37

Hi,

Here is the list of elements handled by gmshToFoam:

Code:

// Element type numbers
static label MSHTRI   = 2;
static label MSHQUAD  = 3;
static label MSHTET   = 4;
static label MSHPYR   = 7;
static label MSHPRISM = 6;
static label MSHHEX   = 5;

So, no high-order meshes.

In fact, meshing the cylinder like you have attached to the message in general does not require high order elements.

hewei · February 6, 2015, 09:39

Thanks!!
so in order to improve the quality of the surface, just adding more points, right?

W.

Quote:

Originally Posted by alexeym

Hi,

Here is the list of elements handled by gmshToFoam:

Code:

// Element type numbers
static label MSHTRI   = 2;
static label MSHQUAD  = 3;
static label MSHTET   = 4;
static label MSHPYR   = 7;
static label MSHPRISM = 6;
static label MSHHEX   = 5;

So, no high-order meshes.

In fact, meshing the cylinder like you have attached to the message in general does not require high order elements.

alexeym · February 6, 2015, 11:16

Quote:

Originally Posted by hewei

Thanks!!
so in order to improve the quality of the surface, just adding more points, right?

W.

Yes, also you can use mesh grading to increase density just near the surface of cylinder.

opedrofunk · February 6, 2015, 13:07

You might have a look at this:

https://extensions.sketchup.com/en/c...y-tetgen-tools

Some quick screen shots (multi region mesh, smooth mesh gradation):

I wrote this plugin to solve a problem I was having (namely, that design iterations were happening extremely quickly, and the corresponding simulation/setup times needed to be similarly reduced), and decided to release it in case it might help others. It's free, of course.

You can control mesh gradation, refine locally, set regions and boundaries, remove sections of the mesh (holes), etc. It works with tetgen - which, of course you can convert directly to OpenFOAM format with the tetgenToFoam utility, and with gmsh if you want to do additional preprocessing before converting with the gmshToFoam utility.

Anyway, I hope this might be helpful to the community.
Peter

hewei · February 6, 2015, 18:12

Quote:

Originally Posted by alexeym

Yes, also you can use mesh grading to increase density just near the surface of cylinder.

Thank you very much Alexey!

hewei · February 6, 2015, 18:15

Thank you very much Peter, I will learn your work, I believe it will not only help me, but also gives others more choice. Thanks you again!!

Wei

Quote:

Originally Posted by opedrofunk

You might have a look at this:

https://extensions.sketchup.com/en/c...y-tetgen-tools

Some quick screen shots (multi region mesh, smooth mesh gradation):

I wrote this plugin to solve a problem I was having (namely, that design iterations were happening extremely quickly, and the corresponding simulation/setup times needed to be similarly reduced), and decided to release it in case it might help others. It's free, of course.

You can control mesh gradation, refine locally, set regions and boundaries, remove sections of the mesh (holes), etc. It works with tetgen - which, of course you can convert directly to OpenFOAM format with the tetgenToFoam utility, and with gmsh if you want to do additional preprocessing before converting with the gmshToFoam utility.

Anyway, I hope this might be helpful to the community.
Peter

February 6, 2015, 07:37		#2
alexeym Senior Member Alexey Matveichev Join Date: Aug 2011 Location: Nancy, France Posts: 1,930 Rep Power: 38	Hi, Here is the list of elements handled by gmshToFoam: Code: // Element type numbers static label MSHTRI = 2; static label MSHQUAD = 3; static label MSHTET = 4; static label MSHPYR = 7; static label MSHPRISM = 6; static label MSHHEX = 5; So, no high-order meshes. In fact, meshing the cylinder like you have attached to the message in general does not require high order elements.

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February 6, 2015, 13:07		#5
opedrofunk Member Peter Join Date: Feb 2015 Location: New York Posts: 73 Rep Power: 11	You might have a look at this: https://extensions.sketchup.com/en/c...y-tetgen-tools Some quick screen shots (multi region mesh, smooth mesh gradation): I wrote this plugin to solve a problem I was having (namely, that design iterations were happening extremely quickly, and the corresponding simulation/setup times needed to be similarly reduced), and decided to release it in case it might help others. It's free, of course. You can control mesh gradation, refine locally, set regions and boundaries, remove sections of the mesh (holes), etc. It works with tetgen - which, of course you can convert directly to OpenFOAM format with the tetgenToFoam utility, and with gmsh if you want to do additional preprocessing before converting with the gmshToFoam utility. Anyway, I hope this might be helpful to the community. Peter