# 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: 12 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: 12 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
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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
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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: 150 Rep Power: 15 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: 10 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,

 February 12, 2017, 00:18 #8 Senior Member   vidyadhar Join Date: Jul 2016 Posts: 138 Rep Power: 9 Hello Chrisi, Can you please let me know what are the units of value 4e-03 in the following sizeDistribution model taken from bubbleCloudProperties file. sizeDistribution { type fixedValue; fixedValueDistribution { value 4e-03; } } I am thinking that it is in meters. Am I right. Please let me know. Thanks & Regards, Vidyadhar

March 26, 2018, 12:09
#9
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Min Zhang
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Quote:
 Originally Posted by Chrisi1984 Hey together, the second colume should be ΔQ3(xi). Kind regards Chrisi

Hello Chrisi,

I have two questions about the sizeDistribution.

1. The second column of generalDistribution is the number/volume/mass fraction of that particular particle/droplet size, yes?
2. You said that "With "uniform" you define a constant droplet size for all your droplets". My question is we could use "uniform" to define a uniform distribution of droplet/particle size, yes?

Thanks and best regards,
Min

March 27, 2018, 15:14
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Quote:
 Originally Posted by minzhang Hello Chrisi, I have two questions about the sizeDistribution. 1. The second column of generalDistribution is the number/volume/mass fraction of that particular particle/droplet size, yes? 2. You said that "With "uniform" you define a constant droplet size for all your droplets". My question is we could use "uniform" to define a uniform distribution of droplet/particle size, yes? Thanks and best regards, Min
Hello together,

Regarding the questions:
1. The first column is the diameter in m. The second column is the volume probability for the corresponding diameter.
2. Yes

Kind regards
Chrisi

March 27, 2018, 15:28
#11
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Min Zhang
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Quote:
 Originally Posted by Chrisi1984 Hello together, Regarding the questions: 1. The first column is the diameter in m. The second column is the volume probability for the corresponding diameter. 2. Yes Kind regards Chrisi

Hello Chrisi,

1. What do you mean by "volume probability", is it the same as "volume fraction"?
2. With "uniform size distribution", I mean it is a distribution between minValue and maxValue, instead of "a single particle size". So I am wondering what is your meaning, the former one or the latter?
3. I want to have three particle sizes and all three corresponding volume/number fractions are the same (equal to 1/3). So I am wondering which type of size distribution (general or uniform) could be used?

Thanks again for your kind help!

Best regards,
Min

March 30, 2018, 18:04
#12
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Min Zhang
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Quote:
 Originally Posted by minzhang Hello Chrisi, Thank you so much for your reply! 1. What do you mean by "volume probability", is it the same as "volume fraction"? 2. With "uniform size distribution", I mean it is a distribution between minValue and maxValue, instead of "a single particle size". So I am wondering what is your meaning, the former one or the latter? 3. I want to have three particle sizes and all three corresponding volume/number fractions are the same (equal to 1/3). So I am wondering which type of size distribution (general or uniform) could be used? Thanks again for your kind help! Best regards, Min

Corrections to Point 3:
3. I want to have three particle sizes and all three corresponding volume/mass fractions are the same (equal to 1/3). So I am wondering which type of size distribution (general or uniform) could be used?

My own understanding:
So I can use the "uniform" distributionModel. Because I need a uniform mass fraction and this is exactly what OpenFOAM "uniform" distributionModel gives.
Am I correct?

April 1, 2018, 13:52
#13
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Min Zhang
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Quote:
 Originally Posted by Azanulbizar 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?

Hello Azanulbizar,

I am wondering whether you could be so kind to have a look at my question.

size distribution models in OpenFOAM 4.x

Your help would be very appreciated!

May 25, 2021, 05:24
#14
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Quote:
 Originally Posted by minzhang Corrections to Point 3: 3. I want to have three particle sizes and all three corresponding volume/mass fractions are the same (equal to 1/3). So I am wondering which type of size distribution (general or uniform) could be used? My own understanding: So I can use the "uniform" distributionModel. Because I need a uniform mass fraction and this is exactly what OpenFOAM "uniform" distributionModel gives. Am I correct?
I have the same question

 May 26, 2021, 04:33 #15 New Member   Join Date: Jun 2017 Posts: 14 Rep Power: 8 I solved problem of having 2 sizes of particles by adding one more injection model with fixedValueDistribution. And it is possible to add as much as you want. injectionModels { model1 { type patchFlowRateInjection; massTotal 1; parcelBasisType mass; massFlowRate 10; patchName inlet; duration 0.5; concentration 2; parcelConcentration 1e8; SOI 0; sizeDistribution { type fixedValue; fixedValueDistribution { value 1e-6; } } } model2 { type patchFlowRateInjection; massTotal 1; parcelBasisType mass; massFlowRate 10; patchName inlet; duration 0.5; concentration 2; parcelConcentration 1e8; SOI 0; sizeDistribution { type fixedValue; fixedValueDistribution { value 2e-6; } } } }

 May 26, 2021, 07:27 #16 Member   Join Date: Jun 2020 Posts: 86 Rep Power: 5 Hey Akimlav I am struggling to understand the patchFlowRateInjection model, as there are not much written about it neither any tutorial available for that. I saw that you used that model for your case, can you please explain the meaning of parameters required for the patchFlowRateInjectionModel, especially the keywords 'concentration' and 'parcelConcentration'? Best Regards Atul

May 26, 2021, 07:36
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Quote:
 Originally Posted by atul1018 Hey Akimlav I am struggling to understand the patchFlowRateInjection model, as there are not much written about it neither any tutorial available for that. I saw that you used that model for your case, can you please explain the meaning of parameters required for the patchFlowRateInjectionModel, especially the keywords 'concentration' and 'parcelConcentration'? Best Regards Atul

Hi!

My knowledge is limited.

patchFlowRateInjection

Don`t know more than what here is said.

I played with the numbers in order to get amount of particles that I need.

Cheers!

 June 1, 2021, 18:00 Size distribution model definition in openfoam8 #18 New Member   Mohamed Zayed Join Date: Sep 2020 Posts: 5 Rep Power: 5 The following definition for the general distribution model is taken from openfoam8/src/lagrangian/distributionModels/general/general.H Code: ```Class Foam::distributionModels::general Description A general distribution model where the distribution is specified as (point, value) pairs. By default the values are assumed to represent a probability density function, but the model also supports specifying a cumulative distribution function. In both cases it is assumed that the function is linear between the specified points. In both modes of operation the values are automatically normalized. SourceFiles general.C```

 January 26, 2022, 11:32 #19 Member   UOCFD Join Date: Oct 2020 Posts: 40 Rep Power: 4 Does anybody know the formulation and mathematical background of the general distribution?? Any paper or somewhere to find?? btw check my new post!! reactingFoam - Particle Size Distribution thanks

 Tags lagrange particle, spraycloudproperties