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Solution changing with dt.

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Old   July 1, 2013, 08:57
Default Solution changing with dt.
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Hi,

I have a code in cylindrical coordinates that uses central differences. My problem is this: when I change the time step size, keeping everything else the same(grid included), I get vastly differing solutions.

Been breaking my head over this - any ideas??

Thanks in advance!
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Old   July 1, 2013, 11:21
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Are you talking about a steasy state problem or an unsteady one?
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Old   July 2, 2013, 01:01
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Its a steady state problem.
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Old   July 2, 2013, 03:18
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Are you using an implicit or explicit solver for this?
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Old   July 2, 2013, 04:25
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Advection terms are explicitly calculated. Viscous terms in the radial direction alone are implicitly calculated.
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Old   July 2, 2013, 05:09
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I think that the discussion of your problem must be better focused:
- what variable you see that strongly change with dt?
- what about the cell Re number? are you sure to fulfill the stability constraint?
- have you experienced the same behavior for refined h steps?
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