Residuals in transient modeling

destroy · January 15, 2018, 05:42

Hello,

I'm performing analysis of the flow throught some geometrical object, which temperature is rising. After some timesteps, the scaled residuals for the every timestep starts from the level that is considered as converged (10e-3 for the flow and 10e-6 for energy). The temperature is still rising. Is there a necessity of using >1 iteration for timestep in this situation?

Regards
Destroy

LuckyTran · January 15, 2018, 15:27

Sorry I can't follow what you are trying to say about residuals.

But, at each time-step, you need enough iterations for the temperature at that time to converge. This means that at each time-step, you need to see the residuals drop to your convergence criteria (1e-03 for continuity and 1e-06 for energy) before moving onto the next time-step. You should also monitor the temperature vs iteration at each time-step to see that the temperature has converged.

January 15, 2018, 05:42	Residuals in transient modeling	#1
destroy Member Marcin Join Date: Jun 2016 Posts: 96 Rep Power: 9	Hello, I'm performing analysis of the flow throught some geometrical object, which temperature is rising. After some timesteps, the scaled residuals for the every timestep starts from the level that is considered as converged (10e-3 for the flow and 10e-6 for energy). The temperature is still rising. Is there a necessity of using >1 iteration for timestep in this situation? Regards Destroy

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January 15, 2018, 15:27		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 66	Sorry I can't follow what you are trying to say about residuals. But, at each time-step, you need enough iterations for the temperature at that time to converge. This means that at each time-step, you need to see the residuals drop to your convergence criteria (1e-03 for continuity and 1e-06 for energy) before moving onto the next time-step. You should also monitor the temperature vs iteration at each time-step to see that the temperature has converged.