### Author Topic: UDF for discrete phase model  (Read 16015 times)

#### lakhi

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##### UDF for discrete phase model
« on: August 06, 2012, 02:45:51 PM »
Hi. I'm working with air dust mixture. Does anybody have udf (or tell me some other way) to find the number of dust particles trapped in and number of dust particles escaped from a cyclone from the start till the convergence of the problem? The particles have a range of diameter. I'm not a programmer, so I need help. Efforts will be highly appreciated.
« Last Edit: August 06, 2012, 02:52:04 PM by lakhi »

#### mali28

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##### Re: UDF for discrete phase model
« Reply #1 on: August 06, 2012, 03:04:42 PM »
With each discrete phase iteration, you get to see how many parcels are tracked, how many parcels are trapped and how many escape from the boundary.

#### lakhi

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##### Re: UDF for discrete phase model
« Reply #2 on: August 06, 2012, 03:18:05 PM »
Thanx mali28 4 reply. The thing is that I set mass flow rate and velocity in the dpm with normal to face injection and I didn't set start and stop time (both by default 0). At the end of simulation it says like "particles tracked = 760" and "particles trapped = 0" and "particles escaped = 0". In the mid of the problem I have something like "particles tracked = 86907" and "particles trapped = 208" and "particles escaped = 4" and so on. This means my particles tracked value goes on decreasing at some interval till the end. Am I doing something wrong? Is it possible to inject a certain number of particles and then keep the track? Plz. help !

#### mali28

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##### Re: UDF for discrete phase model
« Reply #3 on: August 06, 2012, 05:15:03 PM »
At some point in time you will have maximum number of particles, but then particles will start to escape from the domain, at some point in simulation, a pseudo steady state will be reached. In which the number of particles at any time in the domain will be nearly constant. The number of tracked particles should not decrease at the end of simulation if your injection is continuous.

#### lakhi

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##### Re: UDF for discrete phase model
« Reply #4 on: August 07, 2012, 08:03:58 AM »
Thanx mali28, I got it. As in your last line"The number of tracked particles should not decrease at the end of simulation if your injection is continuous.", you are right ! That is what is making me to think about my approach. If I set mass flow rate and velocity in the dpm with normal to face injection and if I set start (as 0) and stop time (as 0.5 sec) my solution does not converge and number of particles tracked is very high. Moreover DPM iteration takes toooo long and fluctuations takes place in residuals. That is the reason why I asked that Is it possible to inject a certain number of particles and then keep the track? I'm really upset with my problem and I'm unable to figure it out. Any suggestions regarding DPM injection please !  Efforts will be praised.
« Last Edit: August 07, 2012, 08:06:23 AM by lakhi »

#### lakhi

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##### Re: UDF for discrete phase model
« Reply #5 on: August 11, 2012, 05:21:21 AM »
Anybody! Some idea how to sort out the problem??