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Francesca Rossi (francesca)
New member
Username: francesca

Post Number: 2
Registered: 12-2003
Posted on Wednesday, February 04, 2004 - 07:16 am:   

I need to set two different initial temperature values in two different adjacent region. How can I do it?
Thank you very much
Francesca Rossi
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Robert G. Nelson (rgnelson)
Moderator
Username: rgnelson

Post Number: 102
Registered: 06-2003
Posted on Wednesday, February 04, 2004 - 04:05 pm:   

If you declare your initial values in terms of a defined name, you can set the value by region.

DEFINITIONS
U0 = default_initial_value
INITIAL VALUES
U = U0
BOUNDARIES
REGION 5
U0 = different_initial_value

Be careful with this, though. Discontinuous initial conditions can lead to very steep transient waves, which cause tiny initial timesteps and massive mesh refinement at the discontinuity. If you can create a smooth transition, the problem will run faster.
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Francesca Rossi (francesca)
Junior Member
Username: francesca

Post Number: 3
Registered: 12-2003
Posted on Thursday, February 05, 2004 - 03:26 am:   

Thank you very much for your replay. I will try it!
Francesca Rossi
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Keely Wray (keely)
New member
Username: keely

Post Number: 1
Registered: 07-2004
Posted on Thursday, July 01, 2004 - 02:04 pm:   

I also needed to define my initial values in this way, and I tried using the example above, but the program keeps telling me the defined name (in the above example it would be UO) is an illegal symbol in the Boundaries/Region area. What should I do?
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Robert G. Nelson (rgnelson)
Moderator
Username: rgnelson

Post Number: 172
Registered: 06-2003
Posted on Friday, July 02, 2004 - 01:20 am:   

You must have made a syntactic error.
Send me the file, or post it here.
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Keely Wray (keely)
New member
Username: keely

Post Number: 2
Registered: 07-2004
Posted on Friday, July 02, 2004 - 12:07 pm:   

The file is attached. The initial value is zero except in Region 4. I was also wondering if an IF THEN ELSE statement in the definitions section could be used to define the value of co, and then just have c=co in the initial values section. I also tried this, but then it said that IF was an illegal symbol.

application/octet-stream
KWChemfluxSquare_Square.pde (9.7 k)
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Robert G. Nelson (rgnelson)
Moderator
Username: rgnelson

Post Number: 174
Registered: 06-2003
Posted on Friday, July 02, 2004 - 04:11 pm:   

When you redefine the value of a parameter in a region, the redefinition must appear after the REGION tag and before any START statements - that is, the redefinition cannot be inside of any boundary path (see "Problem Descriptor Reference | Sections | Boundaries | Reassigning Regional Parameters").

You have placed your "co" redefinition after a "feature" statement. Parameters cannot be redefined on features, because they are assumed to be material properties, and a feature has no material.

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