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-   -   Histogram on a selected volume, Droplet diameter profile (http://www.cfd-online.com/Forums/star-ccm/117916-histogram-selected-volume-droplet-diameter-profile.html)

crevoise May 17, 2013 06:12

Histogram on a selected volume, Droplet diameter profile
 
Hi everybody

I am currently computing an injection of water droplets into a cylinder pipe.

I am trying to plot the droplets diameters profile.
For this purpose, when plotting the profile for the entire pipe, I am using the Plot>Histogram option. I am then getting the histogram representing my droplet diameter distribution on all the pipe (actually, of the Lagrangian Phase, as I must select the Lagrangian phase as the part to be plotted).

I have several questions concerning Histogram and field functions:

1/My concern is the following: I wish to plot such histogram only on a small part of my pipe, not the entire pipe. Does anyone know how to make a volume selection in order to plot the histogram of field functions values restricted only to that volume?

2/ One solution I tried was to define afield function defined only on a part of the pipe ( for example ($$Position[0] < 0.5) $ParticleDiameter : 0) is defining a new field function with the droplet diameters from X=0 to 0.5, and putting the diameter to 0 for droplets situated at the end of the pipe.
However, when I will plot, it will report also n droplet of diameter 0, which is not really stisfactory.

3/ I was thinking to first export the Particle Diameter to a Table, to then extract the data (Diameter and Particle Count) for the desire position, but I do not success to make it work. If someone have some hint to do this?

4/ On additional question is about the field function ParticleCount. What does it represent exactly? When I am reading the values, it shoes for example, 0.5. However, when I plot the histogram weightin the droplet diameter with the DropletCount function, the count can go up to 30 (which I like)
When I export a histogram table, it names ParticleCount as 'ParticleCount - average", with value 0.5, then 'ParticleCount - sum' and gives the value 30, and finaly, I can get a 'ParticleCount - accum' which is the cumulative sum of the droplet count for each bin.
I am interested in getting 'ParcticleCount - sum', but when you export the field function, you are getting the value of 'ParticleCount - average'.
Does anyone knows how to get directly access to ParticleCount - sum?

Thanks a lot for any help


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