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Size Distribution Models - Spray Modelling

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Old   May 9, 2013, 22:13
Default Size Distribution Models - Spray Modelling
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Jack Lee
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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.
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Old   May 11, 2013, 05:35
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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
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Old   June 11, 2013, 21:18
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Jack Lee
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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?
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Old   June 1, 2016, 05:11
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Quote:
Originally Posted by Chrisi1984 View Post
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?

Thanks for your help.
kind regards,
Alaska
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Old   June 8, 2016, 04:25
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Quote:
Originally Posted by Alaska1964 View Post
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
Hey Alaska,
I have the same question? what does the second column mean?
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Old   June 8, 2016, 12:40
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Hey together,

the second colume should be ΔQ3(xi).

Kind regards
Chrisi
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Old   June 9, 2016, 08:14
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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,
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