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May 6, 2013, 04:53 
DPM mass flow rate

#1 
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sajeesh
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Hi
During iteration it is showing Injecting 1 particles with mass 2.72272e12 this is not mass flow rate I given mass flow rate as 2.72272 e 9 kg/sec as mass flow rate In the summery result it is showing number as 3.33468 e1 what is that..some body in DPM field pls help me thanking You Sajeesh 

May 7, 2013, 03:25 

#2 
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Philipp
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Let me guess, your timestep is 1.0e3, right?
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May 7, 2013, 03:49 

#3 
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sajeesh
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really thank you for the reply
I was stuck in this problem I had given a time step of 0.001 seconds.and number of time step as 1 and start and stop injection i given is 0.001 and 300 sec respectively to ensure the presence of particle Exactly i want to find out the extra hydraulic resistance produced by the presence of one particle in the flow...by measuring the pressure drop difference with particle and without one p[article Thank you sir pls help me 

May 7, 2013, 04:07 

#4 
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Philipp
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You insert 1 particle of mass 2.72272e12 kg per time step. Your time step is 1.0e3 s. That gives you a mass flow rate of "2.72272e12 kg / 1.0e3 s = 2.72272e9 kg/s". That's what you want. What is the problem?
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May 7, 2013, 04:35 

#5 
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sajeesh
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sir
mass of one particle is volume of particle x density of particle Diamter of particle is 25 micron Volume 4/3 pi r^3 density is 998 kg/m3 so the mass i calculated for one particle is 8.181e15 kg Then after that my channel is 2000 um length Then to cover this distance with flow rate of continous phase 50 ul/min ( oil denisty 840 kg/m3) take nearly 0.003 seconds Then mass flow rate i calculated as mass of one particle *number of partcicle(1) /0.003 kg/sec AS you said this makes me wrong Sir can i know what is meant by number of particle in parcel.A method to set the mass flow rate I want to further discuss with you can i get your email id Any way thanks for your replies 

May 7, 2013, 04:42 

#6 
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Philipp
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Maybe your confusion comes from the difference of particles and parcels.
Fluent Help (16.12.1.4) says: For typical applications, the computational cost of tracking all of the particles individually is prohibitive. Instead, the approach for the discrete element method is similar to that of the DPM, in that like particles are divided into parcels, and then the position of each parcel is determined by tracking a single representative particle. The DEM approach differs from the DPM in the following ways: The mass used in the DEM calculations of the collisions is that of the entire parcel, not just that of the single representative particle. The radius of the DEM parcel is that of a sphere whose volume is the mass of the entire parcel divided by the particle density. Also: The mass flow rate of your inlet DPM phase has nothing to do with the size of your domain. It is just "injected mass per time step / time step size".
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May 7, 2013, 05:46 

#7 
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sajeesh
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sir
Its very helpful for me. During iteration it is showing I particle tracked 1 particle escaped at Some time 3 particle tracked 1 escaped ( ie is it mean two particle remain in the domain) Can i say it as a two particle of my specified diameter 25 micron or parcel. If it is parcel please explain me. some time At the end of iteration it is showing 1 particle tracked and 1 escaped.So it mean that no particle in the domain. Sir one more help how can i animate these particle tracking.Movement of partcle with time In workbench CFD post it is taking only trk files.But how can i get trk file in FLUENT... Thank you.With out your help i may proceed the mass flow rate calculation with domain time Thanks sajeesh 

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