Running transient with steady results as initial conditions

cwl · November 24, 2016, 12:46

Hi

To my great embarrassment i found out - that i do not know any easy way to run transient simulation using steady run results as initial conditions (same simulation, same physics etc).

Obviously i can change physics from steady to unsteady, but i want it to run from very beginning to the end without my interference i.e. manual switching or recording any macro (Run steady -> Converge -> Switch physics -> Run transient) - so i'm pretty sure there is much easier and natural way.

Please, tell me i'm an eejit and give a hint %>

me3840 · November 28, 2016, 18:17

No, there is no non-manual intervention for this. The best way is to write a macro.

You can in theory set a large timestep with a huge number of inner iterations and then reduce it once the 'steady' part converges with a field function, but I would recommend using the macro.

cwl · November 29, 2016, 05:06

Thank you for you reply :>

That's awful, even CFX has got this feature :-\
Yep, macro will work, - but will make life a bit more complicated in case of automated runs like Optimate.

me3840 · November 29, 2016, 09:17

Optimate has a feature to allow a macro to run during the run, so it shouldn't be a big deal.

cwl · November 29, 2016, 10:31

It's not a big deal, it's another minor issue - instead of setting a kind of "computational sequence" in Star (like Solve Steady -> Solve Transient), there is a need to use macro.
I just mean that unnecessary complexities better be avoided.
I'm pretty sure - we'll see this feature in the nearest future .. although it took few years to implement different colors for bodies in CAD-editor

November 24, 2016, 12:46	Running transient with steady results as initial conditions	#1
cwl Senior Member Chaotic Water Join Date: Jul 2012 Location: Elgrin Fau Posts: 438 Rep Power: 18	Hi To my great embarrassment i found out - that i do not know any easy way to run transient simulation using steady run results as initial conditions (same simulation, same physics etc). Obviously i can change physics from steady to unsteady, but i want it to run from very beginning to the end without my interference i.e. manual switching or recording any macro (Run steady -> Converge -> Switch physics -> Run transient) - so i'm pretty sure there is much easier and natural way. Please, tell me i'm an eejit and give a hint %>

November 28, 2016, 18:17		#2
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 25	No, there is no non-manual intervention for this. The best way is to write a macro. You can in theory set a large timestep with a huge number of inner iterations and then reduce it once the 'steady' part converges with a field function, but I would recommend using the macro. cwl likes this.

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November 29, 2016, 05:06		#3
cwl Senior Member Chaotic Water Join Date: Jul 2012 Location: Elgrin Fau Posts: 438 Rep Power: 18	Thank you for you reply :> That's awful, even CFX has got this feature :-\ Yep, macro will work, - but will make life a bit more complicated in case of automated runs like Optimate.

November 29, 2016, 09:17		#4
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 25	Optimate has a feature to allow a macro to run during the run, so it shouldn't be a big deal.

November 29, 2016, 10:31		#5
cwl Senior Member Chaotic Water Join Date: Jul 2012 Location: Elgrin Fau Posts: 438 Rep Power: 18	It's not a big deal, it's another minor issue - instead of setting a kind of "computational sequence" in Star (like Solve Steady -> Solve Transient), there is a need to use macro. I just mean that unnecessary complexities better be avoided. I'm pretty sure - we'll see this feature in the nearest future .. although it took few years to implement different colors for bodies in CAD-editor