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Transient simulation -> Steady state solution

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Old   October 31, 2014, 01:22
Default Transient simulation -> Steady state solution
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I have a query regarding transient simulations.

In case a transient simulation produces a steady state solution after progressing for a certain time, how is it possible to confirm such trend.

I mean is this done generally by looking at some monitor points.

And if a steady solution exists to such problems why is it not possible to achieve it by a steady state simulation directly instead of running a transient simulation for a certain time.

Could someone please provide a clarification to this

Best regards,
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Old   October 31, 2014, 04:26
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The main reason is because if the flow has transient behaviour then a steady state simulation will never converge because it is not steady. These flow transients are very common in fluid flows - they occur as vortex streets off bluff bodies, at separations jiggling about and at laminar to turbulent transition with laminar separation bubbles which jiggle about.
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Old   October 31, 2014, 10:08
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You very possibly could achieve the same result using a steady simulation, but your residuals won't converge as Glenn says. Instead you would monitor the result of interest and your imbalances to determine convergence, instead of the residuals.
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Old   October 31, 2014, 10:29
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A faster way of getting the solution is to run a steady state solution and get as close to a steady state solution as you can, and then switch to transient simulation. You effectively reduce how long you spend in transient mode and shorten the overall combined run time.
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