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OpenFOAM] Can I plot the lagrangian particle velocity to field velocity 

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February 11, 2019, 21:53 
OpenFOAM] Can I plot the lagrangian particle velocity to field velocity

#1 
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Seokwon Whang
Join Date: May 2012
Posts: 25
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I tried to post the Lagrangian data. Especially, I want to post the particle velocity on certain line.* (I use reactingParcelFoam, and there are*no particles which are exactly on the line.)
Therefore, I think that the Lagrangian particle data in the time folder (0/reactingCloud1/ U, T, position,*etc.) should be converted into the field data. (Is it right?) How can I*convert the Lagrangian data to*Eulerian data in OpenFOAM? 

February 12, 2019, 07:44 

#2  
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Andrew Somorjai
Join Date: May 2013
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Quote:
The best solution I've see so far for plotting your data was this thread Sampling lagrangian data "1. start paraFoam 2. load the lagrangian data in addition to the "regular" data 3. "Split off" the lagrangian data using the "Extract Block"filter 4. Open a new view on the result and make that view a "Spreadsheet view". In that view you will see the raw lagrangian data 5. File>Export that view to a CSVfile" 

February 13, 2019, 21:36 

#3 
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Seokwon Whang
Join Date: May 2012
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Thank you for answering my question.
If I follow your answer, I get the “point data” for each lagranian particle, not the “field data”. What I want to do is to convert this “point data” to “field data”. Thank you again for your reply. 

February 13, 2019, 22:30 

#4  
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Andrew Somorjai
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Quote:
Say you have two equally massed particles in a cubic cm at an instant and they have a mass of 2 grams, so then in that cell you can compute what density is and there's your Euler data, but two seconds later the particles with different vectors now occupy two cells each and now each cell has half the density. Writing the program to do this is possible, just use hashing like octrees or something, it's just complicated and needs tons of ram. Maybe someone else could explain a better solution, regards. 

September 8, 2019, 22:07 

#5  
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liguangze
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September 11, 2019, 16:15 

#6 
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Join Date: Dec 2018
Location: Darmstadt, Germany
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I have some doubts if this is really what you want. Usually, you will have a limited amount of parcels (or real particles) in each computational cell. The number will probably not be large enough to create meaningful statistics in one cell. If you want a representative velocity for your particle phase in a cell, I think you have to gather the particles crossing that cell over time and calculate a mean or rms velocity by using the velocity moments of the resulting distribution. This a similar to calculating the SMD of a distribution, only that you are working with velocities. Hope this helps. Cheers RP


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