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Re: [ff3d-users] Memory error

From: Stephane Del Pino
Subject: Re: [ff3d-users] Memory error
Date: Wed, 04 Feb 2004 13:22:33 +0100

Robert Li wrote:
> Dear Stephane Del Pino,
>   I met a memory error when I tried to test my
> example.
> I need both plane boundary and whole box boundary.
> Therefore, I defined the domain, which is made of six
> planes, is as same as box.
This is definitely not a good idea!
As I said if your planes do coincide with the box faces you might get
numerical errors that will lead to wrong mesh.
If your computationnal domain is the box, please use xmin, xmax,...
instead of POV-like boundaries.
Use the FEM syntax
solve (u) in M
        u = g on M xmin;

>  Can I use this method to get both plane boundary and
> whole box boundary?

I think no.

when you write
domain O = domain(S, (inside(<1,0,0>) and
inside(<0,1,0>) and inside(<0,0,1>) and inside(<1,1,0>) and
inside(<1,0,1>) and
inside(<0,1,1>) ) or (inside(<0.9,0,0>) and inside(<0,0.9,0>) and
inside(<0,0,0.9>) and inside(<0.9,0.9,0>) and inside(<0.9,0,0.9>) and
inside(<0,0.9,0.9>)) or inside() or inside(<0.9,0.9,0.9>));
I think it does not what you expect:
Looking to your POV-Ray file, 'inside(<1,1,1>) or inside(<0.9,0.9,0.9>)'
is equivalent to 'inside(<0.9,0.9,0.9>)' since the <0.9,0.9,0.9> box
containes the <1,1,1> box ...

Could you please clarify what is the exact problem you want to solve?
If it is something like
-div(mu*grad(u)) = ...
where mu varies in different layers, the way to do it is very simple and
do not depend on FDM if your geometry is a box. If it is that, I will
explain to you.
Please give as much details as you can.

> >>>>output<<<<
> oops: Something strange happened: incorrect mesh:
>         One of the faces of your mesh is related to 4
> cells (vertices: )

This is a surface mesher error (a failure while trying to built the
connectivity). I think that Cecile will look at it --- it may be another
mesh failure due to bad data.

Best Regards,

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