CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

about group injection of DPM model

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 27, 2004, 23:41
Default about group injection of DPM model
  #1
zwdi
Guest
 
Posts: n/a
Hello everyone, I am using group injection type in DPM model. The total mass flow rate for the particle is 10g/s. I set the number of particle stream is 1,000. And the number of tries is 10. Now I am confused about how much value I should set for mass flow rate of each particle stream in the following point properties.(i.e. mass flow rate for the first point and mass flow rate for the last point)Is it 10g/s devided by 10 or 10g/s devided by 10000? And another question: If I want to set the particle uniform diameter about 1e-06m, could I choose the diameter distribution as linear and then for the first point and the last point, I set the same value(1e-06)? Does anybody have clear conception on these knowledge and give me a help? Thanks in advance for sharing idea with me. Best regards, Zwdi
  Reply With Quote

Old   March 30, 2004, 09:45
Default Re: about group injection of DPM model
  #2
David
Guest
 
Posts: n/a
hello,

concerning the particle uniform diameter, you are right, you should use a linear distribution with first and last point same value.

if you set the number of particle stream to 1,000 then you can divide your mass flow rate by 1,000 as it will allocate the mass flow rate for each particle stream.

i hope this helps

David
  Reply With Quote

Old   March 30, 2004, 13:20
Default Re: about group injection of DPM model
  #3
zwdi
Guest
 
Posts: n/a
Thank you very much, David.

In your response, you didn't mention what is the number of tries for. I just want to make sure if the flow rate for first point and last point is the total mass flow rate divided by 1000(number of particle stream), without relaitonship with number of tries(such as 10). Please give me response if I understand your answer correctly.

Thanks again

Zwdi
  Reply With Quote

Old   March 30, 2004, 13:29
Default Re: about group injection of DPM model
  #4
David
Guest
 
Posts: n/a
Hi,

you're welcome for the response.

This is the Fluent definition for the Number Of Tries:

"Specify the number of tries.

An input of zero tells FLUENT to compute the particle trajectory based on the mean continuous phase velocity field (Equation 19.2-1), ignoring the effects of turbulence on the particle trajectories.

An input of 1 or greater tells FLUENT to include turbulent velocity fluctuations in the particle force balance. The trajectory is computed more than once if your input exceeds 1: two trajectory calculations are performed if you input 2, three trajectory calculations are performed if you input 3, etc. Each trajectory calculation includes a new stochastic representation of the turbulent contributions to the trajectory equation. When a sufficient number of tries is requested, the trajectories computed will include a statistical representation of the spread of the particle stream due to turbulence. "

Is it cleared to you now?

so you dont need to include the number of tries in your calculation so you divide by 1,000 only.

i hope this helps

regards

David
  Reply With Quote

Old   April 2, 2004, 14:18
Default Re: about group injection of DPM model
  #5
zwdi
Guest
 
Posts: n/a
Hello David, Sorry for responsing so late. Thank you very much. Have a good weekend. Zwdi
  Reply With Quote

Old   April 12, 2004, 20:31
Default Re: about group injection of DPM model
  #6
David
Guest
 
Posts: n/a
Hi Zwdi,

please read this:

When multiple stochastic trajectory calculations are performed, the momentum and mass defined for the injection are divided evenly among the multiple particle/droplet tracks, and are thus spread out in terms of the interphase momentum, heat, and mass transfer calculations. Including turbulent dispersion in your model can thus have a significant impact on the effect of the particles on the continuous phase when coupled calculations are performed.

so i hope it clarifies it all

regards

David
  Reply With Quote

Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to put melting point data of inert particle in DPM model of Fluent subhankar_bhandari FLUENT 0 July 28, 2010 08:40
How to put melting Point data of inert particle in DPM model subhankar_bhandari Main CFD Forum 0 July 26, 2010 08:28
Constant velocity of the material Sas CFX 15 July 13, 2010 09:56
Are my IRIXbs systune parametersb setting correct lakeat OpenFOAM Installation 1 May 5, 2008 11:48
DPM injection ritmat FLUENT 6 June 26, 2007 03:38


All times are GMT -4. The time now is 13:42.