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Old   January 23, 2008, 09:46
Default Range of Additional Variable
Gauranga Das
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While solving for an additional varaible, I see that the solution shows some unrealistic values for the same (negative values). How can I impose a condition on the solver such that any values of the variable less than 0 should be made equal to 0?


Gauranga Das
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Old   January 23, 2008, 10:24
Default Re: Range of Additional Variable
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Dear Gauranga Das.

If you are worried about post-processing, you can create a new variable in CFX-Post, and make it equal to your Additional Variable and bound it on both limits.

The negative values are there for a reason:

1 - Skew meshes allow unbounded solutions. How good is your mesh? If you improve (refine, better quality) your mesh, do the negative values go away?

2 - The solver cannot clip the solution variable; otherwise, the solution will never converge. The negative value is acceptable (though unrealistic in your particular case) for the discrete equations.

3 - Is your solution well converged? Perhaps, it is a temporary artifact of the iteration process.

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