irregular flow

pato · February 6, 2012, 05:58

hi,

i´m modeling a flow in a channel going upwards through a porous media(1cm thick), instead of doing it throug the perforated plate. The velocity profile i get at the beginning of the channel is very discontinuous, being negative and positive, and very irregular.

Could someone help me to find a solution in order to reduce this irregularities and have only positive upwards flow?

Thanks!

ghorrocks · February 6, 2012, 19:10

Are you sure you have adequately converged?

pato · February 7, 2012, 03:04

actuially i had to stop the simulation since they were very long. Nevertheless the masas and momentum were not changing anymore. What parameter should i change to make it converge?

rideway · February 7, 2012, 03:14

I dont know if it is your mistake, but last week i was facing a similar problem and the (stupid) mistake was that i wasnt using double precision. If not, try to refine the mesh. Also check that the bouyancy is properly defined if you used it.

pato · February 7, 2012, 04:37

what do you mean with double precision?

rideway · February 7, 2012, 05:04

I meant that in the Solver Manager (called Solution in Workbench) you can choose which precision you want to use, Run priority and other stuff.

When you open the Solver Manager, in the Define Run window, there are two folders: Solver and Interpolator. I marked the Double Precision Override in both of them and then I had no problems anymore.

February 6, 2012, 05:58	irregular flow	#1
pato Member albert Join Date: Jan 2012 Posts: 31 Rep Power: 14	hi, i´m modeling a flow in a channel going upwards through a porous media(1cm thick), instead of doing it throug the perforated plate. The velocity profile i get at the beginning of the channel is very discontinuous, being negative and positive, and very irregular. Could someone help me to find a solution in order to reduce this irregularities and have only positive upwards flow? Thanks!

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February 6, 2012, 19:10		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Are you sure you have adequately converged?

February 7, 2012, 03:04		#3
pato Member albert Join Date: Jan 2012 Posts: 31 Rep Power: 14	actuially i had to stop the simulation since they were very long. Nevertheless the masas and momentum were not changing anymore. What parameter should i change to make it converge?

February 7, 2012, 03:14		#4
rideway New Member Anonymous Join Date: Feb 2012 Location: Germany Posts: 13 Rep Power: 14	I dont know if it is your mistake, but last week i was facing a similar problem and the (stupid) mistake was that i wasnt using double precision. If not, try to refine the mesh. Also check that the bouyancy is properly defined if you used it.

February 7, 2012, 04:37		#5
pato Member albert Join Date: Jan 2012 Posts: 31 Rep Power: 14	what do you mean with double precision?

February 7, 2012, 05:04		#6
rideway New Member Anonymous Join Date: Feb 2012 Location: Germany Posts: 13 Rep Power: 14	I meant that in the Solver Manager (called Solution in Workbench) you can choose which precision you want to use, Run priority and other stuff. When you open the Solver Manager, in the Define Run window, there are two folders: Solver and Interpolator. I marked the Double Precision Override in both of them and then I had no problems anymore.