HELP: Transient Simulation on a Cluster

MaherEid · October 6, 2019, 15:55

Hello,
I am running a fluent transient simulation on a Cluster.
After some time steps fluent stops at the "Updating solution at time levels N and N-1 Done"
All nodes are still 100% running yet the next time step won't be solved.
I have no idea if it is a fluent problem or from the cluster and i waited 1 full day.

If anyone might have a solution/suggestion please let me know asap.
Thanks!

LuckyTran · October 7, 2019, 15:35

Fluent is done. If you check your cpu load, it's probably 0%.

Check your settings and figure why it's not doing more time-steps. My guess, you have some convergence criteria set that's telling Fluent "it's done"

MaherEid · October 7, 2019, 16:34

I set time step number to 100000 but it only does 1 or 2 and stops.
The cpu loads are still at 100%.
The same case works fine on any single machine but the problem seems to be occurring on a cluster only

Светлана · October 7, 2019, 19:38

What fluent version are you using? Can you please consider running another simulation on the cluster, something simpler like flow past a cylinder. Does it work correctly or not.

MaherEid · October 8, 2019, 03:16

I tried versions 17.2, 19R1, 19R3
I ran a simpler flow over a cylinder and it works fine

Светлана · October 8, 2019, 04:04

What are the differences between the two simulations. Try increasing complexity, set it to transient, add any other missing physics or setup.

At the same time try to decrease complexity of your original model: make it laminar model, isothermal, etc as simple as you can even if this makes no sense for the physics.
Does this come up with anything meaningful? If this is not a big or confidential problem, upload your fluent .cas file and I can give it a try.

LuckyTran · October 8, 2019, 10:21

Run out of ram?

MaherEid · October 8, 2019, 10:29

No there's plenty of RAM left

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
How to stop transient simulation which has been run from scheme script?	AlexanderZ	FLUENT	8	August 31, 2017 04:25
Transient RANS Simulation	Bazinga	Main CFD Forum	5	June 21, 2017 11:21
the problem of my transient simulation "Floating point exception: Overflow "	alloveyou	CFX	15	November 22, 2012 11:14
Beginning a Transient Simulation	Norflow	CFX	2	October 7, 2011 00:38
Resume Transient simulation	HMR	CFX	1	June 28, 2011 21:13

October 7, 2019, 15:35		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,675 Rep Power: 66	Fluent is done. If you check your cpu load, it's probably 0%. Check your settings and figure why it's not doing more time-steps. My guess, you have some convergence criteria set that's telling Fluent "it's done"

October 7, 2019, 16:34		#3
MaherEid New Member M.Eid Join Date: Apr 2018 Posts: 27 Rep Power: 8	I set time step number to 100000 but it only does 1 or 2 and stops. The cpu loads are still at 100%. The same case works fine on any single machine but the problem seems to be occurring on a cluster only

October 7, 2019, 19:38		#4
Светлана Senior Member Svetlana Tkachenko Join Date: Oct 2013 Location: Australia, Sydney Posts: 407 Rep Power: 14	What fluent version are you using? Can you please consider running another simulation on the cluster, something simpler like flow past a cylinder. Does it work correctly or not.

October 8, 2019, 03:16		#5
MaherEid New Member M.Eid Join Date: Apr 2018 Posts: 27 Rep Power: 8	I tried versions 17.2, 19R1, 19R3 I ran a simpler flow over a cylinder and it works fine

October 8, 2019, 04:04		#6
Светлана Senior Member Svetlana Tkachenko Join Date: Oct 2013 Location: Australia, Sydney Posts: 407 Rep Power: 14	What are the differences between the two simulations. Try increasing complexity, set it to transient, add any other missing physics or setup. At the same time try to decrease complexity of your original model: make it laminar model, isothermal, etc as simple as you can even if this makes no sense for the physics. Does this come up with anything meaningful? If this is not a big or confidential problem, upload your fluent .cas file and I can give it a try.

October 8, 2019, 10:21		#7
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,675 Rep Power: 66	Run out of ram?

October 8, 2019, 10:29		#8
MaherEid New Member M.Eid Join Date: Apr 2018 Posts: 27 Rep Power: 8	No there's plenty of RAM left