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-   -   Particle size distribution DPM (http://www.cfd-online.com/Forums/fluent/106163-particle-size-distribution-dpm.html)

barzin August 21, 2012 05:03

Particle size distribution DPM
 
Hi everyone

Regarding particle size distribution in FLUENT the only available functions are Rosin Rameler (RR) and Uniform distribution. So what if I have my own distribution or even my own injection with a unique condition (e.g velocity, PSD,...). I was wondering if this can be introduce to FLUENT using a file injection?? If yes, how am I suppose to do that? what about the use of UDF? Can anyone explain this to me since I have a very vague vision of this. Your prompt suggestions are most appreciated :)

mali28 August 24, 2012 05:37

Quote:

Originally Posted by barzin (Post 377938)
Hi everyone

Regarding particle size distribution in FLUENT the only available functions are Rosin Rameler (RR) and Uniform distribution. So what if I have my own distribution or even my own injection with a unique condition (e.g velocity, PSD,...). I was wondering if this can be introduce to FLUENT using a file injection?? If yes, how am I suppose to do that? what about the use of UDF? Can anyone explain this to me since I have a very vague vision of this. Your prompt suggestions are most appreciated :)

You can use several injections, each having a different size and different flow rate but injecting from the same location. That will make your own size distribution.

barzin August 24, 2012 06:02

Quote:

Originally Posted by mali28 (Post 378506)
You can use several injections, each having a different size and different flow rate but injecting from the same location. That will make your own size distribution.

Hey mali

Thank you so much for your reply. This is a nice trick but do you think it is handy when you have a a very wide distribution. I mean hundreds of diameters??? How can this be done by a UDF?? Have you got any idea?

mali28 August 24, 2012 06:17

Quote:

Originally Posted by barzin (Post 378511)
Hey mali

Thank you so much for your reply. This is a nice trick but do you think it is handy when you have a a very wide distribution. I mean hundreds of diameters??? How can this be done by a UDF?? Have you got any idea?

If you have a wide range of sizes, then you will need to add more bins. But if you add more bins then your simulation will become more computationally expensive. So it has to be a compromise between computational time and accuracy. You can check the sensitivity of results on the number of discrete sizes (bins).
And select the one which is the best compromise between the computational time and accuracy.

barzin August 24, 2012 06:36

Is this "Bin" defined by "Number of diameters" in the injection properties dialogue box? If yes the only particle size distribution which includes this feature is Rosin Ramler. So if I select RR for my injections again the overall distribution will be RR? am I right?

mali28 August 24, 2012 07:03

Quote:

Originally Posted by barzin (Post 378515)
Is this "Bin" defined by "Number of diameters" in the injection properties dialogue box? If yes the only particle size distribution which includes this feature is Rosin Ramler. So if I select RR for my injections again the overall distribution will be RR? am I right?

Yes, bin is defined by number of diameters. You also check the simulation sensitivity with the number of parcles (tracks) for each discrete size.
Fluent only offers Rosin-Rammler distribution. Log-normal distribution can also be used but it is not available in Fluent.

barzin August 24, 2012 07:30

Right, cool. Thanks a lot for your time mate :)

chang February 27, 2014 06:07

Quote:

Originally Posted by mali28 (Post 378520)
Yes, bin is defined by number of diameters. You also check the simulation sensitivity with the number of parcles (tracks) for each discrete size.
Fluent only offers Rosin-Rammler distribution. Log-normal distribution can also be used but it is not available in Fluent.

What if i want to obtain Log-normal distribution? through the UDF or use R-R instead? Thanks!


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