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June 1, 2015, 09:26 
mass flow rate in DPM steady tracking

#1 
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hi all
i want to inject a single particle (mass = 0.001 kg) in a flow, and track the particle using steady DPM. but in the 'Set Injection Properties' dialog box, it asks for the flow rate (kg/sec)..so how do i decide this flow rate... should it be (1) just the mass of the 1 particle, like 0.001 kg/s or (2) particle area * density * flow velocity at the injection point if option (1) then the problem is that i want to inject only 1 particle, so using 0.001 kg/s will mean something else..isn't it? and if option (2) then how do I know the velocity at the injection point? do i have to run the simulation without DPM first, get the flow velocity at injection point, and then use it to calculate the mass flow rate. i am just a bit confused about this flow rate thing.. if anyone has any idea, please share... thanks a lot.. 

June 1, 2015, 09:58 

#2 
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That flow rate is relevant for postprocessing of your results. If you have two sources of particles, and one source gives 0.1 kg/s and the other 0.3 kg/s, you put those numbers and Fluent will do the relevant postprocessing, while it (at minimum) only needs to calculate two trajectories. It does not influence the trajectory calculation in any way, at least not when the DPM and flow solution are uncoupled.
In your case, you don't need this kind of postprocessing, so you can put any number you want. Make it 1 kg/s, and you are done. 

June 1, 2015, 10:14 

#3  
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hi thanks for such a quick reply
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so what does that flow rate actually mean: is it the rate at which the particle is moving in the flow or is it the rate at which the particle is injected into the flow sorry for asking so many questions, i just want to know it properly. thanks so much for ur quick reply 

June 1, 2015, 10:27 

#4  
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But, as I said, you are not going to do that kind of postprocessing. So in your case it is just a label that will not be used for anything. You can enter your age, your phone number of your favourite Reynolds number, it does not matter. 

June 1, 2015, 10:44 
thanks a lot :)

#5  
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and thanks so much for helping me out, now i am clear about the problem i had..thanks so much... and can i ask one more favor from u, since u have already been so helpful.....i asked another question in the forum yesterday but didnt get any proper reply, it is also about/related to DPM only.. if u dont mind, can u see that question too, and give some suggestions...i feel u may know what to do..here is the link to the question: http://www.cfdonline.com/Forums/flu...mecavity.html sorry for asking so many questions... thanks so much again 

Tags 
discrete phase model, dpm fluent, injection model, mass flow rate, steady state 
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