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May 9, 2013, 22:13 
Size Distribution Models  Spray Modelling

#1 
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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 RosinRammler, 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:
Kind regards Chrisi 

June 11, 2013, 21:18 

#3 
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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? 

June 1, 2016, 05:11 

#4  
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Alaska1964
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Quote:
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 

June 8, 2016, 04:25 

#5 
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Ping Chang
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June 8, 2016, 12:40 

#6 
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Hey together,
the second colume should be ΔQ3(xi). Kind regards Chrisi 

June 9, 2016, 08:14 

#7 
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Alaska1964
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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, 

February 12, 2017, 00:18 

#8 
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vidyadhar
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Hello Chrisi,
Can you please let me know what are the units of value 4e03 in the following sizeDistribution model taken from bubbleCloudProperties file. sizeDistribution { type fixedValue; fixedValueDistribution { value 4e03; } } 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:
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 

#10  
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Quote:
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:
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 

March 30, 2018, 18:04 

#12  
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Min Zhang
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Quote:
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:
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:


May 26, 2021, 04:33 

#15 
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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 1e6; } } } 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 2e6; } } } } 

May 26, 2021, 07:27 

#16 
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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 

#17  
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Quote:
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 
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Mohamed Zayed
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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 
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UOCFD
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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 

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lagrange particle, spraycloudproperties 
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