# Size Distribution Models - Spray Modelling

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 May 9, 2013, 22:13 Size Distribution Models - Spray Modelling #1 New Member   Jack Lee Join Date: Jan 2013 Location: Alberta Posts: 5 Rep Power: 5 Hi, I am wondering if anyone can explain to me how does the size distribution models work and what kind of input I have to put it? In spray modelling, instead of using Rosin-Rammler, how does one use distribution models such as fixed, general, etc etc which is located in /src/lagrangian/distributionModel If not mistaken, I got a feeling that they are based on some Cumulative Distribution Function or some probability function. If anyone can refer to me what to look up for, I would also deeply appreciate it. Thank you very much.

May 11, 2013, 05:35
#2
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Hi,

with "general" you can give a volume probabilty for the droplet size in form of a table:

Quote:
 sizeDistribution { type general; generalDistribution { distribution ( ( 0.000075 2.752E-03 ) ( 0.000125 1.000E-02 ) ( 0.000175 1.331E-02 ) ( 0.000225 1.642E-02 ) ( 0.000275 2.058E-02 ) ( 0.000325 2.535E-02 ) ( 0.000375 3.005E-02 ) ( 0.000425 3.416E-02 ) ( 0.000475 3.737E-02 ) ( 0.000525 3.967E-02 ) ( 0.000575 4.104E-02 ) ( 0.000625 4.166E-02 ) ( 0.000675 4.157E-02 ) ( 0.000725 4.100E-02 ) ( 0.000775 3.990E-02 ) ( 0.000825 3.866E-02 ) ( 0.000875 3.699E-02 ) ( 0.000925 3.531E-02 ) ( 0.000975 3.358E-02 ) ( 0.001025 3.160E-02 ) ( 0.001075 2.979E-02 ) ( 0.001125 2.800E-02 ) ( 0.001175 2.616E-02 ) ( 0.001225 2.441E-02 ) ( 0.001275 2.276E-02 ) ( 0.001325 2.119E-02 ) ( 0.001375 1.968E-02 ) ( 0.001425 1.825E-02 ) ( 0.001475 1.691E-02 ) ( 0.001525 1.565E-02 ) ( 0.001575 1.449E-02 ) ( 0.001625 1.342E-02 ) ( 0.001675 1.239E-02 ) ( 0.001725 1.142E-02 ) ( 0.001775 1.052E-02 ) ( 0.001825 9.688E-03 ) ( 0.001875 9.023E-03 ) ( 0.001925 8.307E-03 ) ( 0.001975 7.638E-03 ) ( 0.002025 7.016E-03 ) ( 0.002075 6.440E-03 ) ( 0.002125 5.912E-03 ) ( 0.002175 5.551E-03 ) ( 0.002225 5.116E-03 ) ( 0.002275 4.700E-03 ) ( 0.002325 4.312E-03 ) ( 0.002375 3.954E-03 ) ( 0.002425 3.625E-03 ) ( 0.002475 3.324E-03 ) ( 0.002525 3.153E-03 ) ( 0.002575 2.937E-03 ) ( 0.002625 2.706E-03 ) ( 0.002675 2.490E-03 ) ( 0.002725 2.291E-03 ) ( 0.002775 2.108E-03 ) ( 0.002825 1.940E-03 ) ( 0.002875 1.789E-03 ) ); } }
With "uniform" you define a constant droplet size for all your droplets.

Kind regards

Chrisi

 June 11, 2013, 21:18 #3 New Member   Jack Lee Join Date: Jan 2013 Location: Alberta Posts: 5 Rep Power: 5 HI. It took me awhile. but I figured that out already. Thank you very much anyway. By the way, do you have any idea of how to plot the velocity of the parcels/particles using paraview? When I select a plane, and use "plot over a line", I cant obtain the velocities of the parcels. Is there anyway of easily measuring the velocity of the parcels?

June 1, 2016, 05:11
#4
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Quote:
 Originally Posted by Chrisi1984 Hi, with "general" you can give a volume probabilty for the droplet size in form of a table: With "uniform" you define a constant droplet size for all your droplets. Kind regards Chrisi

Dear Chrisi,
Is the second column indicating the cumulative distribution (Q3(xi)) ? And the first column diameter of the particle in meters?

kind regards,

June 8, 2016, 04:25
#5
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Ping Chang
Join Date: Feb 2016
Location: Perth
Posts: 88
Rep Power: 2
Quote:
 Originally Posted by Alaska1964 Dear Chrisi, Is the second column indicating the cumulative distribution (Q3(xi)) ? And the first column diameter of the particle in meters? Thanks for your help. kind regards, Alaska
I have the same question? what does the second column mean?

 June 8, 2016, 12:40 #6 Senior Member   Join Date: Jan 2010 Location: Stuttgart Posts: 146 Rep Power: 8 Hey together, the second colume should be ΔQ3(xi). Kind regards Chrisi Alaska1964 likes this.

 June 9, 2016, 08:14 #7 New Member   Alaska1964 Join Date: May 2015 Posts: 16 Rep Power: 3 Thanks a lot Chrisi, I also think so since the summation of all data on second column is 1. I have another question regarding the particle size distribution. Is there any model in OpenFOAM for log normal PSD? there is a models for "normal" and "RosinRammler", but not for "lognormal". I have data with X50 X90 and geometrical size distribution (GSD). Do you have any idea how I can implement them to my spray model? I also have the data of ΔQ3(xi) for different intervals of diameter. Cheers,

 Tags lagrange particle, spraycloudproperties

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