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Old   January 11, 2012, 08:24
Default Steady vs. Transient
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Hi,

I'm modeling an explicit porous disk inside a water tank. I run a steady and transient simulations, with the only difference between them is the scheme used for each simulation, SIMPLEC for steady and PISO for transient.

Results are very different!! See figures. The wake region in the transient simulation is way shorter tan for the steady simulation.

Does anybody know THE WHY of this disagreement??


Fig-1: Steady simulation.



FFig-2: Transient simulation.
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Old   January 11, 2012, 14:03
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Ryne
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It is my understanding that the transient case gives more of an instantaneous solution at a given time and the steady solution is given as a time averages one.
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Old   January 11, 2012, 20:36
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Rhyno466,

I think the problem was that I didn't run the transient simulation for enough time. I did so, and wake length for the transient simulation is getting similar to the steady case.
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Old   January 13, 2012, 23:49
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Quote:
Originally Posted by egge24 View Post
Rhyno466,

I think the problem was that I didn't run the transient simulation for enough time. I did so, and wake length for the transient simulation is getting similar to the steady case.
There should not be any differences between a steady and transient simulation if all else (boundary conditions, models) are the same. Since more things are likely to go wrong in a transient simulation than a steady one, most likely your transient simulation was not run properly. Keep trying.
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