# Discrete Phase Model, outlet mass flow rate does not fit

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 September 3, 2015, 02:52 #21 Member   Eduardo Tola Join Date: Aug 2015 Location: Madrid/Haifa Posts: 50 Rep Power: 10 Finally, I am using udf =), it a an upgrade that everyone has to do!! I have been having a look, and the macro that you told me is perfect to calculate my goal (P_FLOW_RATE). However I am having two problems: 1-. The one that it seems to be easy. I don't know how to make a loop all over the particles in order to calculate the average flow rate. 2-. The one that it is a little more complex. I don't know how to implement the last funtion only to the particles that crosses a determinated surface in a determinated time. I thought about implementing a if statment checking every face ID with 'Lookup_Thread(domain, ID)'. Is there a easier way? __________________ Having fun with CFD =)

 September 3, 2015, 06:00 #22 Member   Eduardo Tola Join Date: Aug 2015 Location: Madrid/Haifa Posts: 50 Rep Power: 10 I have found the function begin_particle_cell_loop(p,c,t). But it does not work for me. /////////////////////////////////////////////////////////////////////////////////////// #include "udf.h" #include "dpm.h" DEFINE_ADJUST(sum_flow_rate, domain) { int z=0; real sum=0; cell_t c; Thread *t; Particle *p; begin_c_loop(c, t) {begin_particle_cell_loop(p,c,t) { z=z+1; sum=sum+P_FLOW_RATE(p); //fprintf (fp,"%d %g %g \n",z,P_DIAM(p),P_MASS(p)); } end_particle_cell_loop(p,c,t) } printf("SUM OF TOTAL FLOW RATE OF PARTICLES [Kg/s]%s\n",sum/z ); end_c_loop(c, t) } /////////////////////////////////////////////////////////////////////////////////////// 1.- While running, Fluent shows me the following error: 'structure reference not implemented' for the line were 'begin_particle_cell_loop(p,c,t)' is written' 2-. And to calculate that on a surface, would it be just adding: /////////////////////////////////////////////////////////////////////////////////////// int ID=(Number of surface); Thread *thread = Lookup_Thread(domain, ID) /////////////////////////////////////////////////////////////////////////////////////// I don't think that (2-.) would work, but then I don't know how to do it Thank u very much in advance!! __________________ Having fun with CFD =)

 September 17, 2015, 02:42 #23 New Member   Unnikrishnan T P Join Date: Sep 2015 Location: Chennai, India Posts: 27 Rep Power: 10 Hi, I am sorry if this is not of ur interest. In my steady dpm simulation, no of particles is less than no of parcels. Is this posssible? And edu_aero, can u provide some details of ur solution? ie ur case, no of parcels, Total no of particles, and total no of iterations?pls? (From the summary from reports in Fluent postprocessing) Im facing some serious problems thats why...

September 17, 2015, 04:03
#24
Member

Eduardo Tola
Join Date: Aug 2015
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Quote:
 Originally Posted by unnikrishnan Hi, I am sorry if this is not of ur interest. In my steady dpm simulation, no of particles is less than no of parcels. Is this posssible? And edu_aero, can u provide some details of ur solution? ie ur case, no of parcels, Total no of particles, and total no of iterations?pls? (From the summary from reports in Fluent postprocessing) Im facing some serious problems thats why...
'Real'_Nš_of_particles=Nš_Parcels x Nš_Particles
By real number of particles I mean the total number of particles. In general the information that you get from Fluent is the average information of particles in a parcel. In general, you cannot access the information of particles.

Parcel=Group of paticles wih similar conditions. Fluent gives you the information of the mean
And the number of particles per parcel can be constant or change, so it can be that Nš of particles is less than Nš of parcel.

Now, I cannot provide you the information but later I will try to upload it here
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 September 17, 2015, 05:51 Case #25 New Member   Unnikrishnan T P Join Date: Sep 2015 Location: Chennai, India Posts: 27 Rep Power: 10 Im sorry. no need to provide ur information. Here are few lines from the summary i got... Total number of parcels : 3304 Total number of particles : 8.998298e+02 Total mass : 1.817365e-04 (kg) Overall RR Spread Parameter : 1.526257e+01 Maximum Error in RR fit : 3.362975e-01 Overall RR diameter (D_RR): 9.943840e-04 (m) Maximum RMS distance from injector : 4.432617e-01 (m) Maximum particle diameter : 1.000000e-03 (m) Minimum particle diameter : 2.424513e-04 (m) So the second line is the no of particles per parcel ri8? (Anyway it's a floating number, just to confirm)

September 17, 2015, 06:47
#26
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Eduardo Tola
Join Date: Aug 2015
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Rep Power: 10
Quote:
 Originally Posted by unnikrishnan Im sorry. no need to provide ur information. Here are few lines from the summary i got... Total number of parcels : 3304 Total number of particles : 8.998298e+02 Total mass : 1.817365e-04 (kg) Overall RR Spread Parameter : 1.526257e+01 Maximum Error in RR fit : 3.362975e-01 Overall RR diameter (D_RR): 9.943840e-04 (m) Maximum RMS distance from injector : 4.432617e-01 (m) Maximum particle diameter : 1.000000e-03 (m) Minimum particle diameter : 2.424513e-04 (m) So the second line is the no of particles per parcel ri8? (Anyway it's a floating number, just to confirm)
I think that it is the average of particles per parcel. You can get the information and check it in:

Results -> Graphics and Animations -> Particle Tracks
Now select the injection, tick in Reoorting type Current positions and report to file
Then export the file and check the number of particles per parcel and you will know if it is correct
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 September 18, 2015, 01:51 #27 New Member   Unnikrishnan T P Join Date: Sep 2015 Location: Chennai, India Posts: 27 Rep Power: 10 I had the report taken earlier and the average no of particles per parcel is around 0.4 I did the particle tracking with "colour by: particle number per parcel" in the dialogue box. And I saw that the colour scale was varying between 0.15 and 11.7. Maximum of 11.7 particles per parcel only? How is that possible??

September 18, 2015, 04:31
#28
Member

Eduardo Tola
Join Date: Aug 2015
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Rep Power: 10
Quote:
 Originally Posted by unnikrishnan I had the report taken earlier and the average no of particles per parcel is around 0.4 I did the particle tracking with "colour by: particle number per parcel" in the dialogue box. And I saw that the colour scale was varying between 0.15 and 11.7. Maximum of 11.7 particles per parcel only? How is that possible??
It doesn't make sense, parcel number has to be a natural number. The only one than can be a real number is the average.

Also number of particles per parcel has to be more than one
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 September 18, 2015, 06:53 #29 New Member   Unnikrishnan T P Join Date: Sep 2015 Location: Chennai, India Posts: 27 Rep Power: 10 Have you tried plotting particle tracks with "colour by: Particle number in parcel" ?? If yes, what range does it vary in?? Please reply it's important Also my second question is, there are many options in the colour by box in particle track dialogue box. Out of these they have the options like colour by particle mass and color by parcel mass. How are they gonna colour these large no of particles in the stream

 February 3, 2020, 08:38 Particle Summary #30 New Member   Aizh Join Date: Jan 2020 Posts: 3 Rep Power: 6 Hi, I'm working with DPM injections. 1) Exactly, used surface case, and i chose inlet where 4018 surfaces. But i can not control the number of particles. I'm using unsteady DPM. My questions: How i can control the number of particle? 2) When i look to summary there are shown that Total number of parcels : 120458 Total number of particles : 4.855374e-06 How number of particle could be non integer number? What is parcel mean? What is the relationsheap between particle and parcel 3) When i look to the Particle Mass Concentration there are shown results in -15 th degree.

 Tags discrete phase model, dpm, fluent 15, injection, mass flow rate