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-   -   Looking for Free Mesh Generator? (http://www.cfd-online.com/Forums/main/3738-looking-free-mesh-generator.html)

Scott Lippman July 28, 2001 00:42

Looking for Free Mesh Generator?
 
If you are looing for a free mesh generator, try TrueGrid(http://www.truegrid.com). Actually it is expensive, but you can use trial version. I've been uing it for years. Not for free now. It makes hexa.

Quality? Just ask anyone who is doing simulation of fluid or structure at Livermore National Labs. I bet nine out of ten people recommend it over other preprocessors.

But keep it mind, your IQ suhould be at least 140 to use it without training.

Scott Lippman.

John C. Chien July 28, 2001 14:24

Re: Looking for Free Mesh Generator?
 
(1). Mesh generation is not difficult at all. (2). In 2-D, 3 points will define a triangle, and 4 points will give you a quad. You don't need a PhD from nuclear research lab to do that. (3). In 3-D, you just add one more point to get a four sided tet cell, and four more points will give you a brick hexa cell. (4). I think, biggest problem the government lab has is they tend to work on very general problems and try to create a program to cover all solutions. (5). So, the challenge they have is how to create a program which will give you any solution which might required in the future. (6). While the CFD need is very simple, that is to create a grid for a very specific problem so that the solution to that problem can be obtained. (7). Going through the general algorithm approach to get a specific solution is attractive to both scientific and political world. But, in the end, it will fail, because individual problem to be solved is very "specific". (8). Communism fails because it can not be used for a large group of people. A large stable group of people will multiply quickly, and the poor state will become even more poor. (9). So, quick, efficient solution must be developed for every specific problem, so that the solution to the specific problem can be obtained. (10). The failure of dot.com, company merger, etc., all share the common features with the concept of a general mesh generation program, that is "trying to invent a general algorithm, then trying to use it for very specific problem". Since it is hard to do so to get a good solution or a mesh this way, failure is guaranteed. (11). Still looking for a general system to shoot down a missile with another one? (12). So, I think, using the wrong approach, it is going to be difficult even with IQ greater than 140. A person is always looking for a general program or algorithm, because he does not even understand what specific problem he is going to solve. (13). Your information simply states that such general code exists, but the solution to the specific problem is still waiting to be discovered.

Dr Strangelove July 30, 2001 15:22

Re: Looking for Free Mesh Generator?
 

You might start looking at this site

Suffice it to say, there are lots of mesh generation packages out there, depending on your needs, your expertise and your budget.



John Chawner August 11, 2001 14:12

Re: Looking for Free Mesh Generator?
 
You write "mesh generation is not difficult at all", make an analogy with communism, and predict that general meshing programs will suffer the same fate as dot.coms.

With all due respect, I think you're over simplifying.

John C. Chien August 13, 2001 11:45

Re: Looking for Free Mesh Generator?
 
(1). You are absolutely right. (2). What I was trying to say is, for simple problems the mesh generation is fairly simple. (3). On the other hand, if the gemoetry itself is complex, then it will take a while to put together a mesh. But this is not because of mesh generation problem. It is because the geometry is not simple. (4). I must say that most people look at the mesh generation from geometry point of view. So, in 3-D, it becomes very difficult. (5). On the other hand, if you look at the basic requirement of a brick-type, tet-type cell or grid, and cover the computational domain section by section, then the task is very simple. (6). So, the key issue is in the topology. Geometry with different topology requires different way to to create a mesh. (7). This weekend, I wrote a program using VC++ in console mode to solve a standard lid driven cavity flow problem, with stretching mesh. On my new 400 dollars computer, it took only a few second to reach converged solution for a mesh size of 51x51 at Re=1000. It took a couple of minutes to get a converged solution for 101x101 case at Re=1000. The 1001x1001 case requires only about 65Meg RAM to run on PC. ( I don't think this problem requires 1 Giga mesh size to compute. it just to show that you it is possible to run such problem on ordinary PC/ 1GHZ speed) (8). I am thinking about making these high speed code and high accuracy solution available for cfd readers as a reference tool. In this way, you will get the real feeling of a real cfd code and solution. I don't have a schedule for that task. But my idea is to make each case available at a book rate. (9). In other words, for a person with experience, mesh and cfd solution is easy and fast. For complex geometry problem, if you handle it section by section, it will become a very simple problem also.

jackmarlowe January 24, 2010 01:16

Leaving all that discussion about IQ's and failing reasons of various foundations behind, is there a simple meshing program where I can open my CAD model and put some nodes around and determine the intervals between those nodes? (Other than ICEM)
I am looking for a really simple one - and may be looking it under "free mesh generator" thread is not wise but I am off words searching it...

Ahmed January 24, 2010 10:52

Quote:

Originally Posted by jackmarlowe (Post 243579)
Leaving all that discussion about IQ's and failing reasons of various foundations behind, is there a simple meshing program where I can open my CAD model and put some nodes around and determine the intervals between those nodes? (Other than ICEM)
I am looking for a really simple one - and may be looking it under "free mesh generator" thread is not wise but I am off words searching it...

Quality Free mesh generators tend to be optimized for a specific application which in most cases differ from your application, for instance take a look at this one, https://www.ccad.uiowa.edu/mimx/IA-FEMesh/ but its input files are image files produced by medical scanning devices, Honesty speaking, I do not know how to convert image files to that format.
Then take another look to a more popular one, Gmsh http://www.geuz.org/gmsh/
it can do what you are talking about, but you need to recompile it with OpenCascade support so you can import and export files using the popular file formats such as stl, iges, brep etc...
Finally you have salome pre and post processor, www.salome-platform.org take a look at the tutorials available on their web portal, it might be the one you are looking for. You can also look http://www.megacads.dlr.de/
The price of Free mesh generators, is that the developing teams do not offer technical support other than a web page and their attitudes when you find a bug and report it, is not, in most cases, what you would expect from a commercial product.
There are other free mesh generators, search this forum or the web for other similar posts.
Good luck

jackmarlowe January 24, 2010 15:21

Thank you Ahmed, that was all I asked for :)
I am going to look into those.

CFDtoy January 27, 2010 12:05

mesh gen
 
i have posted links to some free mesh gens in my blog.

Quote:

Originally Posted by jackmarlowe (Post 243579)
Leaving all that discussion about IQ's and failing reasons of various foundations behind, is there a simple meshing program where I can open my CAD model and put some nodes around and determine the intervals between those nodes? (Other than ICEM)
I am looking for a really simple one - and may be looking it under "free mesh generator" thread is not wise but I am off words searching it...


Ahmed January 27, 2010 16:51

Please add MEDUSA personal to your blog
 
Quote:

Originally Posted by CFDtoy (Post 243939)
i have posted links to some free mesh gens in my blog.

CFDtoy
it seems that your blog is not accessible, I guess you could write the address explicitly
Please add this address to your blog
http://www.cad-schroer.com/index.php...Start&land=com
Medusa competes against proE, runs on Linux or Windows, you get a 6 month license that can be renewed as long as you are not using it for commercial gains.
Good Luck to all especially those looking for FreeCAD

The forum administrators are rightfully against embeded (hidden) advertising, but your blog does not fall under this category

Ahmed January 27, 2010 17:01

Quote:

Originally Posted by jackmarlowe (Post 243615)
Thank you Ahmed, that was all I asked for :)
I am going to look into those.

feedback will benefit other readers, so please consider it


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