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Void Fraction??? - DEM

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Old   September 4, 2014, 11:41
Default Void Fraction??? - DEM
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Yesaswi
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Hi,

I have particles in a domain and I am trying to find the surface averaged void fraction on a plane in the domain. (attached image 1) (color scale for plane only, not for the particles) (particles scales for their actual size) (I switched on two way coupling).

The void fraction is clearly less than it should be (0.98 is a lot of empty space). So I changed the transparency of the particles.(attached image 2)

We can see that only the mesh cells, where the particle centroids are located have a local void fraction of 0.25 (Blue colored cells amidst red cells). All the others cells, have void fraction of 1, irrespective of the fact the a portion of particles still stay in the mesh cells. Thus the area averaged volume fraction is reporting wrong value.

Is there anyway I can correct this to detect the actual void fraction? Am I using the void fraction in a wrong manner? I couldn't find the function definition in the user manual too.

Thank You
Yesaswi
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Old   May 18, 2022, 11:11
Question Area averaged void fraction in DEM, STAR CCM+
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Zahra Ghasemi
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Hi guys,

This is exactly my problem. I want to get the area averaged void fractions for different cross sections within the region. But the surface integral of field function void fraction does not give correct value.

Thank you,
Zahra
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