Hi Jonathan,
oops, I am sorry, I forgot that I am loosing the "scitex.us" association
when I use web mail. Here goes again.
Regards,
Matt Koch
Jonathan Guyer wrote:
Matt,
I don't know if you get notification, but this message got bounced.
Please resend from your scitex.us address, or subscribe the other one;
whichever is easier.
Thanks,
- Jon
On Jan 18, 2007, at 10:29 PM, fipy@nist.gov wrote:
Rejected message: sent to fipy@nist.gov by [EMAIL PROTECTED] follows.
Reason for rejection: sender not subscribed.
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Hi Jonathan,
I have to deal with both a cylinder and a sheet geometry. I think in
order for me to make progress, I'll switch from cylinder to sheet,
which should be doable in rectangular coordinates without too much
fuss. That way, I can focus on what really matters, i.e. implementing
level set Stefan problems in solidification (EFG). I'll start messing
with that now. I am sure there'll be plenty of questions as I get
into this. If I can solve it suceesfully, though, it'll give me the
confidence that it is worth tackling the cylinder coordinates in 3D
later on. Thanks again for your help thus far - I am sure we'll pick
up on this again after some success with the rectangular coordinates.
Regards,
Matt Koch
Jonathan Guyer wrote:
On Jan 18, 2007, at 2:24 PM, Matt Koch wrote:
thanks for the quick feedback. So, if I am not too mistaken, I
might as well view this like modelling a slice of pie in cartesian
(rectangular) 3D space, and applying zero flux, etc., boundary
conditions to the two flanks (planes of constant theta) of the slice?
Exactly.
We really are talking about a 3D model then. No need to talk about
cylindrical coordinates then, simply model an arbitrary shape
(such as a cylinder) in rectangular 3D space?
Not exactly. The slice of pie will only be one cell deep. It's only
a sliver of pie, not a whole slice.
The question then is, how well will a mesh approximate curved
surfaces?
Right, that's a question. Naively, you'd think that you should make
the sliver as thin as possible, so that the difference between the
chord length and the arc length is negligibly small, but I seem to
remember Daniel telling me that it's not that simple. We do think
that it's possible to lie to the mesh so that it thinks that its
faces are curved, but we'll have to test that.
Plus, no matter how thin the slice in 3D, a computational
sacrifice has to be made, because we are dealing with more grid
points in 3D than we would in 2D? Am I getting close, or have I
missed the point?
There's some cost, but not huge. FiPy only evaluates your fields on
cell centers, and you'll have exactly as many cell centers as if
you did things in 2D. The cells will be cuboids in 3D instead of
squares in 2D, so there's a bit of extra computation needed for
that, but it shouldn't be too bad.
