30+ hours for 300k nodes

Springroove · October 31, 2017, 12:21

Hi all,

I am working on a problem comprising a train travelling in an evacuated tube at 300 m/s (M=0.88). However, it takes about 30+ hours to reach about 10,000 iterations which is not even convergence. Does this maybe have to do with my boundary conditions? (I only have 300k nodes and the full domain is 200m x 0.1m)
I've tried different bc's but to no avail. For the latest run I have the following bc's:

Inlet velocity u = 300 m/s and total temperature of 300K
top, bottom and side walls all moving with 300 m/s in x-(flow)-direction
outlet pressure of 100 Pa (which is the ambient tube pressure)
the train is just a no-slip wall

I'm using the SST model
I don't think it's due to my workstation as I am using a laptop which has i7 @2.2 GHz with 16GB RAM.

Cheers!!

ghorrocks · October 31, 2017, 17:47

I suspect it might be related to this FAQ: https://www.cfd-online.com/Wiki/Ansy...gence_criteria

October 31, 2017, 12:21	Boundary conditions - simulation time	#1
Springroove New Member Xilef Smith Join Date: Apr 2017 Posts: 19 Rep Power: 9	Hi all, I am working on a problem comprising a train travelling in an evacuated tube at 300 m/s (M=0.88). However, it takes about 30+ hours to reach about 10,000 iterations which is not even convergence. Does this maybe have to do with my boundary conditions? (I only have 300k nodes and the full domain is 200m x 0.1m) I've tried different bc's but to no avail. For the latest run I have the following bc's: Inlet velocity u = 300 m/s and total temperature of 300K top, bottom and side walls all moving with 300 m/s in x-(flow)-direction outlet pressure of 100 Pa (which is the ambient tube pressure) the train is just a no-slip wall I'm using the SST model I don't think it's due to my workstation as I am using a laptop which has i7 @2.2 GHz with 16GB RAM. Cheers!! Last edited by Springroove; October 31, 2017 at 14:45.

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October 31, 2017, 17:47		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	I suspect it might be related to this FAQ: https://www.cfd-online.com/Wiki/Ansy...gence_criteria