Track after particle hit the wall.

Brigido · October 7, 2013, 06:52

Hi everybody.

I’m doing a steady state simulation with Ansys CFX and using particle transport modeling. I have a problem with the particle track. The track ends a short time before the particle hits an inclined wall (the boundary of the mesh). The wall has a free slip condition.
I want to follow the particle displacement after the impact.

How can I solve this problem?

Thank you!

http://imageshack.us/photo/my-images/809/bpdk.png/

ghorrocks · October 7, 2013, 17:39

There are many reasons a particle track can terminate - exceed time, distance, integration steps, minimum displacement increment. Have you checked which reason caused this particle track to terminate?

Brigido · October 8, 2013, 02:59

Thank you for your answer,

I don’t know the reason why particle track terminate. In fact, some tracks arrive to the wall and go out across the outlet, and other tracks don’t. This last tracks ends a short time before the particle hits the wall.

I realize the track distance varies according to the residuals. If I stop the solver at 1E-3 I can see a short track across the wall. If I stop the solver at 1E-4 or 1E-5, the problem come back.

Thank you again.

Brigido · October 8, 2013, 04:45

Solved!
The problem was the solver control.

Thanks!

ghorrocks · October 8, 2013, 05:23

I trust you are not proposing using a very loose residuals convergence critereon is the "solution" to your problem....

Brigido · October 8, 2013, 05:54

Quote:

Originally Posted by ghorrocks

I trust you are not proposing using a very loose residuals convergence critereon is the "solution" to your problem....

Of course not. My residual convergence criterion is 1E-5…
I changed some parameters of the particle control to solve the problem.

Thanks anyway

ghorrocks · October 8, 2013, 05:56

I am pleased to hear that, very good.

libbyy · October 12, 2013, 13:41

Which parameters were causing the termination before reaching the wall?
I am having similar problems in a transient simulation.

Brigido · October 15, 2013, 09:14

Quote:

Originally Posted by libbyy

Which parameters were causing the termination before reaching the wall?
I am having similar problems in a transient simulation.

I increased max. tracking time and max. tracking distance at particle termination control.

libbyy · October 28, 2013, 13:33

I will try that, thanks!

October 7, 2013, 06:52	Track after particle hit the wall.	#1
Brigido New Member Albert Join Date: Oct 2013 Posts: 5 Rep Power: 12	Hi everybody. I’m doing a steady state simulation with Ansys CFX and using particle transport modeling. I have a problem with the particle track. The track ends a short time before the particle hits an inclined wall (the boundary of the mesh). The wall has a free slip condition. I want to follow the particle displacement after the impact. How can I solve this problem? Thank you! http://imageshack.us/photo/my-images/809/bpdk.png/ Last edited by Brigido; October 7, 2013 at 07:57.

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October 7, 2013, 17:39		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	There are many reasons a particle track can terminate - exceed time, distance, integration steps, minimum displacement increment. Have you checked which reason caused this particle track to terminate?

October 8, 2013, 02:59		#3
Brigido New Member Albert Join Date: Oct 2013 Posts: 5 Rep Power: 12	Thank you for your answer, I don’t know the reason why particle track terminate. In fact, some tracks arrive to the wall and go out across the outlet, and other tracks don’t. This last tracks ends a short time before the particle hits the wall. I realize the track distance varies according to the residuals. If I stop the solver at 1E-3 I can see a short track across the wall. If I stop the solver at 1E-4 or 1E-5, the problem come back. Thank you again.

October 8, 2013, 04:45		#4
Brigido New Member Albert Join Date: Oct 2013 Posts: 5 Rep Power: 12	Solved! The problem was the solver control. Thanks!

October 8, 2013, 05:23		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	I trust you are not proposing using a very loose residuals convergence critereon is the "solution" to your problem....

October 8, 2013, 05:56		#7
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	I am pleased to hear that, very good.

October 12, 2013, 13:41		#8
libbyy New Member Join Date: Oct 2013 Posts: 2 Rep Power: 0	Which parameters were causing the termination before reaching the wall? I am having similar problems in a transient simulation.

October 28, 2013, 13:33		#10
libbyy New Member Join Date: Oct 2013 Posts: 2 Rep Power: 0	I will try that, thanks!