Subject: [fenics-dev] Mesh to FEniCS

From: "tomtzigt" <[email-masked]>
Date: Mon, 21 Nov 2005 17:02:19 -0500

I need some help. I am looking at two different initial meshers: CUBIT and a
fancy industrial mesher from Simmetrix. The latter is completely automatic,
but gives you a tet-mesh. The test case I want to build is some funky
geometry in a flow field and then letting Navier-Stokes loose on it. Before
I spent time translating their mesh descriptions to the FEniCS mesh, the
question I have is, what could possibly go wrong with these two meshers that
I should know about before investing time into the adaptation. 

Theo

---

From: Matthew Knepley <[email-masked]>
Date: Mon, 21 Nov 2005 16:15:35 -0600

"tomtzigt" <[email-masked]> writes:

> :o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns="http://www.w3.org/TR/REC-html40">
>
> I need some help. I am looking at two different initial meshers: CUBIT and a fancy industrial mesher from Simmetrix. The latter is completely automatic, but gives you a tet-mesh. The test case I want to build is some funky
> geometry in a flow field and then letting Navier-Stokes loose on it. Before I spent time translating their mesh descriptions to the FEniCS mesh, the question I have is, what could possibly go wrong with these two meshers that I
> should know about before investing time into the adaptation. :p>

  Never heard of Symmetrix, but both the meshers are not open, so we can't really make changes.
I am not sure what answer you are looking for, however I have written code to take a simple
cell <--> vertices description to a Sieve-type mesh already (C++) which is in PETSc. Is this
what you want or something fancier?

     Matt
-- 
"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec Guiness

---

From: "tomtzigt" <[email-masked]>
Date: Mon, 21 Nov 2005 17:27:26 -0500

Understood, I was planning to do the adaptation code so that FEniCS stays
clean. I see that CUBIT uses EXODUS-II as its mesh format, don't know what
Simmetrix uses, either way, I can use all the direction of someone that has
written a translator before. If that means starting with something you have
laying around, power to me.

The other issues I like to understand up front is what could go wrong with
the actual simulation. CUBIT will produce a hex-mesh (that is their
strength, right?) and Simmetrix will give me a tet-mesh. What type of
problems can I anticipate when using these meshes on a Navier-Stokes PDE?
Remember, I am learning as I go here.

Theo

-----Original Message-----
From: Matthew Knepley [mailto:[email-masked]] 
Sent: Monday, November 21, 2005 5:16 PM
To: tomtzigt
Cc: 'Discussion of FEniCS development'
Subject: Re: [fenics-dev] Mesh to FEniCS

"tomtzigt" <[email-masked]> writes:

> :o="urn:schemas-microsoft-com:office:office"
xmlns:w="urn:schemas-microsoft-com:office:word"
xmlns="http://www.w3.org/TR/REC-html40">
>
> I need some help. I am looking at two different initial meshers: CUBIT and
a fancy industrial mesher from Simmetrix. The latter is completely
automatic, but gives you a tet-mesh. The test case I want to build is some
funky
> geometry in a flow field and then letting Navier-Stokes loose on it.
Before I spent time translating their mesh descriptions to the FEniCS mesh,
the question I have is, what could possibly go wrong with these two meshers
that I
> should know about before investing time into the adaptation. :p>

  Never heard of Symmetrix, but both the meshers are not open, so we can't
really make changes.
I am not sure what answer you are looking for, however I have written code
to take a simple
cell <--> vertices description to a Sieve-type mesh already (C++) which is
in PETSc. Is this
what you want or something fancier?

     Matt
-- 
"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec
Guiness

---

From: Anders Logg <[email-masked]>
Date: Mon, 21 Nov 2005 16:37:37 -0600

> Remember, I am learning as I go here.

FIAT, FFC and DOLFIN only do tetrahedra and triangles (and lines in
the case of FIAT).

/Anders

-- 
Anders Logg
Research Assistant Professor
Toyota Technological Institute at Chicago
http://www.tti-c.org/logg/