Minimum Steps Criterion

AdiHee · November 19, 2021, 07:50

Hey,

I am investigating wing profiles with a time averaged simulation (RANS).However, depending on the angle of attack, the simulation cannot be time averaged. To be able to investigate these cases anyway, I want to average the downforce over the last 300 iterations.
Since the Design Manager stops before reaching 300 itterations if the convergence is sufficient, the averaging is not possible.

My ideas to solve this problem:

1. specify a minimum number of iterations.

Is this possible via the Stopping Criteria -> Fixed Steps?

2. if-statement:
If convergence is reached, then the downforce should not be averaged.
Otherwise the downforce should be averaged.

How can you implement such an expression?

3. do you have any other ideas?

Thanks to all

LuckyTran · November 19, 2021, 22:46

Record a macro.

Set the number of iterations to 300 and turn off the convergence monitor as a stopping criteria.
Iterate/run
Turn on the convergence monitor.
Iterate/run

Add this macro to your design manager

AdiHee · November 20, 2021, 06:54

Unfortunately I´m not very familiar with macros.. Isn´t there a way to implement a criteria witch says:

"Do minimum 300 iterations even tough other stopping criterias are reached"?

LuckyTran · November 20, 2021, 17:52

If that's all you want to do then go to your stopping criteria and change the logical rule from OR to AND

AdiHee · November 21, 2021, 07:42

But which criterion do i need to create that i can change to AND? I tried Stopping Criterion -> New Criterion -> Fixed Steps. But this doesnt work

LuckyTran · November 21, 2021, 21:22

You don't create new criteria. You need to set the existing ones to AND. Star will iterate forever unless your stopping criteria tells it to stop. I don't know your case setup to tell you which ones are stopping it before 300 iterations are done. The default criteria used in every simulation is number of iterations and residuals.

Whichever one is causing it to stop before 300 iterations you need to put to AND as well as number of iterations.

November 19, 2021, 07:50	Minimum Steps Criterion	#1
AdiHee New Member Adi Join Date: Nov 2021 Posts: 4 Rep Power: 4	Hey, I am investigating wing profiles with a time averaged simulation (RANS).However, depending on the angle of attack, the simulation cannot be time averaged. To be able to investigate these cases anyway, I want to average the downforce over the last 300 iterations. Since the Design Manager stops before reaching 300 itterations if the convergence is sufficient, the averaging is not possible. My ideas to solve this problem: 1. specify a minimum number of iterations. Is this possible via the Stopping Criteria -> Fixed Steps? 2. if-statement: If convergence is reached, then the downforce should not be averaged. Otherwise the downforce should be averaged. How can you implement such an expression? 3. do you have any other ideas? Thanks to all

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November 19, 2021, 22:46		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,677 Rep Power: 66	Record a macro. Set the number of iterations to 300 and turn off the convergence monitor as a stopping criteria. Iterate/run Turn on the convergence monitor. Iterate/run Add this macro to your design manager

November 20, 2021, 06:54		#3
AdiHee New Member Adi Join Date: Nov 2021 Posts: 4 Rep Power: 4	Unfortunately I´m not very familiar with macros.. Isn´t there a way to implement a criteria witch says: "Do minimum 300 iterations even tough other stopping criterias are reached"?

November 20, 2021, 17:52		#4
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,677 Rep Power: 66	If that's all you want to do then go to your stopping criteria and change the logical rule from OR to AND

November 21, 2021, 07:42		#5
AdiHee New Member Adi Join Date: Nov 2021 Posts: 4 Rep Power: 4	But which criterion do i need to create that i can change to AND? I tried Stopping Criterion -> New Criterion -> Fixed Steps. But this doesnt work

November 21, 2021, 21:22		#6
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,677 Rep Power: 66	You don't create new criteria. You need to set the existing ones to AND. Star will iterate forever unless your stopping criteria tells it to stop. I don't know your case setup to tell you which ones are stopping it before 300 iterations are done. The default criteria used in every simulation is number of iterations and residuals. Whichever one is causing it to stop before 300 iterations you need to put to AND as well as number of iterations.