# DPM sample report questions

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• Last Post 06 March 2019
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almulhem_900 posted this 06 March 2019

Could someone help with explaining the DPM sample report (for one trajectory) show below:

(          x           y            z            u            v            w     diameter            t    mass-flow         mass    frequency         time         name)
((-2.1816e-01  -1.3009e-01   5.5559e+01  -7.1835e+01  -4.2239e+01  -4.3358e-01   1.8500e-04   3.0000e+02   4.5504e-03   8.7854e-09   5.1795e+05   7.6812e+00) injection-0:861)

I'm injecting the particles through a surface and I'm using a stochastic tracking with 20 tries.

the diameter of each particle I'm specifying is 1.8500e-04 m.  What is the t value of 300 ?

The mass flow of 4.5504e-03 is the mass (8.7854e-09) times the frequency (5.1795e+05). Does that mean every parcel is made of 5.1795e+05 particles ?

If that is true, does fluent do the force balance, when a DPM iteration is done, on the whole parcel that is made the 5.1795e+05 particles with the total equivalent diameter or it uses the diameter of one particle only ?

Thanks

Abdul

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abenhadj posted this 06 March 2019

So what you now pasting is the point property of a parcel.

1/  300 is the default temperature of the particle: not important if you are not enabling energy equation.

2/  It looks after you are running steady state particle tracking: Frequency is the number of particle per second in this parcel @ X, Y and Z. So yes

3/  Yes: the source terms will be then scaled based on the parcel strength so you do not need to worry about that.

Best regards,

Amine

almulhem_900 posted this 06 March 2019

Thanks Amine for the clarification

Could you please elaborate more on my third question? I’m doing a DPM simulation where size (diameter) of the particle is the only variable comparing two cases. So I want to make sure that fluent capture that difference in diameter.

Does the source terms get downscaled to the size of the particle during the DPM iteration and the force balance is applied on the particle scale and consider the diameter of one particle ?

Thanks

abenhadj posted this 06 March 2019

The forces are calculated for that diameter. The trajectory will be then accordingly calculated. The source terms into the carrier phase will be then multiplied with the strength. The strength will be now different.

Best regards,

Amine

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