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Help! -User Difined Functions----Drag Coefficient

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Old   March 13, 2004, 13:10
Default Help! -User Difined Functions----Drag Coefficient
  #1
Colin
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Hi,

I am using Eulerian Model for multiphase flow. In the model, the drag coefficient is 1.0. And I defined the UDF of Drag coefficient as follows:

#include "udf.h"

DEFINE_EXCHANGE_PROPERTY(drag, cell, x_thread, s, f) { Cd = 1.0; return Cd; }

When the UDF is interpreted, Fluent says "Cd" is an undeclared variable. Even if I declare Cd is a real later, Fluent still showed me the same message.

Could someone help me?

Thank you.
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Old   March 14, 2004, 16:04
Default Re: Help! -User Difined Functions----Drag Coeffici
  #2
ap
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Cd is a variable, and you must define it *before* you use it.

Usually, it's a good idea to define variables as local, in order to use them only when needed:


DEFINE_EXCHANGE_PROPERTY(drag, cell, x_thread, s, f)
{
real Cd
Cd = 1.0;
return Cd;
}


or, easier:


DEFINE_EXCHANGE_PROPERTY(drag, cell, x_thread, s, f)
{
return 1.0;
}


Hi

ap
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Old   March 14, 2004, 17:41
Default Re: Help! -User Difined Functions----Drag Coeffici
  #3
Colin
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Thanks AP, I will try as you advised. Colin
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Old   March 14, 2004, 17:52
Default Re: Help! -User Difined Functions----Drag Coeffici
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ap
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I forgot a semicolon in this line, in my first function:

real Cd;

sorry

Hi

ap
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Old   March 15, 2004, 15:10
Default Re: Help! -User Difined Functions----Drag Coeffici
  #5
Colin
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Hi, ap, they work! Thanks.
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Old   March 15, 2004, 20:04
Default Re: Help! -User Difined Functions----Drag Coeffici
  #6
ap
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Great.

Hi

ap
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