I'm trying to check to make sure that the particle distribution injected by Fluent matches the Rosin-Rammler function from Fluent's user guide. My analysis shows that it's not matching.

So my question is, how should I translate the info. from the particle sample file (number of particles for each diameter) into the mass fraction for each diameter.

Thank you

Grant

I contacted Fluent about this and figured out where I was going wrong. So I'm posting the solution here incase someone else runs into this same problem, this is a complete explanation.

The R-R distribution injects a particle stream at each cell along the injection surface, for each particle size. So if you have 144 cells along the injection surface and 13 diameters, then Fluent will inject 1872 particle streams.

Notice that I'm saying streams, not particles. Fluent uses the computed streams to inject a mass flow of particles along those streams. You can see how many total streams for each particle size and the associated flow rates in those streams by selecting report/discrete phase/sample and selecting your injection and a surface along which you want to monitor the particle flow.

To compare the sample data to the R-R exponential function, you determine the mass fraction for each size using the number of particle streams and the associated mass flow rate for each stream.

I hope this helps any of you who run into the same confusion that I did. If you have any questions, just ask.

[shankara.2]

Just a quick question! What is the exact meaning of a 'stream'? Say I have a group injection with 50 particles and turbulent dispersion value of 10, does this mean 500 particles are injected? Or is it 500 particle streams being injected?
Say I want to inject a total of 5000 particles, where does the particle stream come into play and how is related to the total no. of particles?

[Mohsin]

Dear Prashanth

Have you got the answer to your querry?
He means each stream of particle will contain 13 diameters defined by you (in the number of diameters) and by stream he means stream lines... Correct me if I am wrong

[doronzo]

also, stream may mean cluster of particles, so each cluster depends (in terms of mass it can trasport) on mesh, and it represents a group of particles, whose total mass is the one appearing during iterations, calculated as number of injected particles (cluster)/injected mass

??? (not totally sure)

regards

[roukaia]

i'm simulating the compression stroke of ic engine in FLUENT 13. i'm getting pressure only 22 bar at the end of compression stroke (ideal gaz). experimentaly it is around 48bar. why the pressure is not rising the compression ration is about 18
i am using these conditions for intake pressure inlet
gauge total pressure 0
operating condition 10 1352 pascal

exhaust pressure outlet