Reason behind setting DIFFERENT default convergence criteria for continutiy and Energ

vidyadhar · November 30, 2018, 00:02

Hi,

In pressure based solver of Fluent, Why the default values of convergence criteria are set different for continuity, momentum (1e-03 each) and energy (1e-06) equations?

Thanks in advance!
Vidyadhar

LuckyTran · November 30, 2018, 13:20

You have to respect that the majority of Fluent/CFD users are idiots that have no clue what they are doing. On the other hand, they are also the paying customer.

When the default were changed to 1e-06 for everything, a bunch of customers complained that they were no longer able to get "converged" solutions in newer versions of Fluent whereas it was never a problem in older versions. So the response was to change the default "convergence checks" to 1e-03 to make them happy.

Regardless, these values should be user set and the defaults are just there to look pretty. That is, the default values might as well be blank and it shouldn't affect how you approach the case.

November 30, 2018, 00:02	Reason behind setting DIFFERENT default convergence criteria for continutiy and Energ	#1
vidyadhar Senior Member vidyadhar Join Date: Jul 2016 Posts: 138 Rep Power: 10	Hi, In pressure based solver of Fluent, Why the default values of convergence criteria are set different for continuity, momentum (1e-03 each) and energy (1e-06) equations? Thanks in advance! Vidyadhar

November 30, 2018, 13:20		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,763 Rep Power: 66	You have to respect that the majority of Fluent/CFD users are idiots that have no clue what they are doing. On the other hand, they are also the paying customer. When the default were changed to 1e-06 for everything, a bunch of customers complained that they were no longer able to get "converged" solutions in newer versions of Fluent whereas it was never a problem in older versions. So the response was to change the default "convergence checks" to 1e-03 to make them happy. Regardless, these values should be user set and the defaults are just there to look pretty. That is, the default values might as well be blank and it shouldn't affect how you approach the case.