The trajectory calculation of particles injections

Olga · February 1, 2011, 06:17

Hello! I need help.
In my project of small furnuce I used the DPM model and I can't choose optimal max number of steps to complete trajectory calculation. After some iterations the trajectory fats reported as incomplete. Then I increased the max number of steps, but nothing changed. Have you ever faced with similar problem?

Thanks.

amirreza_m · February 1, 2011, 12:29

Hi Olga,
you can decrease step length factor . (this is the number of iteration that a particle remain in one cell) . also you can change the setting in numerics tab wisely.

Olga · February 1, 2011, 21:24

Hi, amirreza!

I forgot to write, that I have already done it. I use the implicit tracking shceme, but I changed it to analytic and varied max number of steps and length scale. Do you know another solution? What is the possible reason of my fail?

Thanks.

amirreza_m · February 2, 2011, 05:20

Hi,
you should solve flow field first and then solve for particle tracking.
to check your numeric settings of particles , you can initialize your flow field with specific velocity magnitude and then view your particle paths or also validate them!

Olga · February 3, 2011, 21:48

Hi, tnx for you quick reply and good advice. I tried to do it and found out, that in my project took place a recirculation zone in any number of steps. Can it be connect with geometry of my project?

Thanks.

amirreza_m · February 4, 2011, 03:20

Hi,
it's not reasonable that you have such small circulation in your domain that particles don't move ! be sure that your flow field results converged by plotting residuals.you can attach schematic of your geometry and boundary conditions here.

Olga · February 5, 2011, 02:21

Hi.
I attached the file with my geometry, boundary conditions and order of my setting.

Thanks for your help.

My project.zip

Amir · February 5, 2011, 08:24

Hi olga,
probably you have decoupled momentum and energy equations (no gravity) and anticipation is that particles were consumed.
I proposed you that first solve for flow field with inert particles . if the problems will remove , you can conclude that something is wrong with your combustion modeling and particle consumption I think .

Olga · February 7, 2011, 04:36

Thank you, Amir. I'll use your advice.

Olga · February 7, 2011, 23:45

Hi, Amir.
I followed your advice and I have new questions.

I thought, that the overall number of trackes is reffered to as "number tracked" which we can see in command line in the time of DPM iteration.
But in Pathlines Diolog box when I compute number tracked released from surface, their sum isn't equal with "number tracked". So, what does it mean?

And the last question

In my project I have one surface released inert injections. But then number tracked is also computed from other surfaces (for example, wall). Does it caused by reflect DP BC type?

Thanks.

Amir · February 8, 2011, 02:37

Hi Olga,
The total number of particles which were tracked was printed in console while particle iterations.
be sure that surfaces from which particles were released have specific and different thread ID from other surfaces like walls.
I think both questions have one answer : you probably include other surfaces to surfaces from which particles were released.
note that in DPM projects you should ensure that particle study is satisfied. you can make virtual surfaces over real ones with arbitrary particles number.

February 1, 2011, 06:17	The trajectory calculation of particles injections	#1
Olga New Member Olga Stavskaya Join Date: Nov 2010 Location: Russia Posts: 11 Rep Power: 15	Hello! I need help. In my project of small furnuce I used the DPM model and I can't choose optimal max number of steps to complete trajectory calculation. After some iterations the trajectory fats reported as incomplete. Then I increased the max number of steps, but nothing changed. Have you ever faced with similar problem? Thanks.

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February 1, 2011, 12:29		#2
amirreza_m New Member Amir Join Date: Nov 2010 Location: Shiraz,Iran Posts: 12 Rep Power: 15	Hi Olga, you can decrease step length factor . (this is the number of iteration that a particle remain in one cell) . also you can change the setting in numerics tab wisely.

February 1, 2011, 21:24		#3
Olga New Member Olga Stavskaya Join Date: Nov 2010 Location: Russia Posts: 11 Rep Power: 15	Hi, amirreza! I forgot to write, that I have already done it. I use the implicit tracking shceme, but I changed it to analytic and varied max number of steps and length scale. Do you know another solution? What is the possible reason of my fail? Thanks.

February 2, 2011, 05:20		#4
amirreza_m New Member Amir Join Date: Nov 2010 Location: Shiraz,Iran Posts: 12 Rep Power: 15	Hi, you should solve flow field first and then solve for particle tracking. to check your numeric settings of particles , you can initialize your flow field with specific velocity magnitude and then view your particle paths or also validate them!

February 3, 2011, 21:48		#5
Olga New Member Olga Stavskaya Join Date: Nov 2010 Location: Russia Posts: 11 Rep Power: 15	Hi, tnx for you quick reply and good advice. I tried to do it and found out, that in my project took place a recirculation zone in any number of steps. Can it be connect with geometry of my project? Thanks.

February 4, 2011, 03:20		#6
amirreza_m New Member Amir Join Date: Nov 2010 Location: Shiraz,Iran Posts: 12 Rep Power: 15	Hi, it's not reasonable that you have such small circulation in your domain that particles don't move ! be sure that your flow field results converged by plotting residuals.you can attach schematic of your geometry and boundary conditions here.

February 5, 2011, 02:21		#7
Olga New Member Olga Stavskaya Join Date: Nov 2010 Location: Russia Posts: 11 Rep Power: 15	Hi. I attached the file with my geometry, boundary conditions and order of my setting. Thanks for your help. My project.zip

February 5, 2011, 08:24		#8
Amir Senior Member Amir Join Date: May 2009 Location: Montreal, QC Posts: 735 Blog Entries: 1 Rep Power: 22	Hi olga, probably you have decoupled momentum and energy equations (no gravity) and anticipation is that particles were consumed. I proposed you that first solve for flow field with inert particles . if the problems will remove , you can conclude that something is wrong with your combustion modeling and particle consumption I think .

February 7, 2011, 04:36		#9
Olga New Member Olga Stavskaya Join Date: Nov 2010 Location: Russia Posts: 11 Rep Power: 15	Thank you, Amir. I'll use your advice.

February 7, 2011, 23:45		#10
Olga New Member Olga Stavskaya Join Date: Nov 2010 Location: Russia Posts: 11 Rep Power: 15	Hi, Amir. I followed your advice and I have new questions. I thought, that the overall number of trackes is reffered to as "number tracked" which we can see in command line in the time of DPM iteration. But in Pathlines Diolog box when I compute number tracked released from surface, their sum isn't equal with "number tracked". So, what does it mean? And the last question In my project I have one surface released inert injections. But then number tracked is also computed from other surfaces (for example, wall). Does it caused by reflect DP BC type? Thanks.

February 8, 2011, 02:37		#11
Amir Senior Member Amir Join Date: May 2009 Location: Montreal, QC Posts: 735 Blog Entries: 1 Rep Power: 22	Hi Olga, The total number of particles which were tracked was printed in console while particle iterations. be sure that surfaces from which particles were released have specific and different thread ID from other surfaces like walls. I think both questions have one answer : you probably include other surfaces to surfaces from which particles were released. note that in DPM projects you should ensure that particle study is satisfied. you can make virtual surfaces over real ones with arbitrary particles number.