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March 4, 2013, 06:58 
problem in particle injection in discrete phase modelling

#1 
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sajeesh
Join Date: Feb 2013
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hi
i am trying to simulate the transient particle tracking in a fluid flow through a square channel.i want to study the transient behavior of a single particle..how i can inject one partilce in to the flow stream... Even i am managed to give group injection and when i am running the code it is showing particle deleted during some iterations..and also in plot particle tracking result option.no tracking of particle have been done...any body can help me 

March 4, 2013, 12:27 

#2 
Super Moderator

have you check unsteady ??? if yes look at your stop time in injection, it should be of a large value so injection never stops.


March 4, 2013, 12:43 

#3 
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sajeesh
Join Date: Feb 2013
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thank you sir.
Sir i am doing unsteady..but sir in ansys user guide i saw if we put start time and stop time as zero..injection will be onlly in the starting of calculation...sir exactly i need one particle in the flow.... My problem defnition is initially i have no particle so i apply mass flow rate as inlet condition and preesure as outlet boundary condition..after simulation i will get inlet pressure also...so the total preesure drop i can found out\ \ I need all the above things when a solid sphere is moving unsteadily in the fluid.the present condition is as follows.initially solid sphere is placed in the fluid.it is taken by the drag force acting on it.later this sphere will modify the flow as two way coupling..after that steady state reached... sir in this model how i get one particle instead of one stream of particle Sir i am not sure my approach is correct..pls g 

March 4, 2013, 12:45 

#4 
Super Moderator

in your injection, how many particle are you giving ??


March 4, 2013, 13:01 

#5 
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sajeesh
Join Date: Feb 2013
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i have no answer for that...i dont know to calculate that also....i given the inlet condition as single
x y and z velocity as zero mass flow rate of particle a low value as 8e14 kg/sec to make the particle as one per minute.... but during the calculation in console 'particle trapped one ' it is showing after some iteration' particle escaped one ' showing ...even we stop iteration before escping particle ..i search for the result as follows the plot and animation particle tracking particle ID'' no result is showing as a result now i have doubt in setiing the particle time step and fluid time step .....how i should set up that.i didnt understand these things from user guide 

March 4, 2013, 15:30 

#6 
Senior Member
AA Azarafza
Join Date: Jan 2013
Posts: 187
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I had such problem before. I think you need to have a deep look at the fluent user guide concerning simulation setup and setting parameters model for step time, step size and etc. Maybe you better to start a steady state and after get enough experience change to unsteady. I don't know how I solved the problem now but I can recommend you that the key to solve the problem lies in step time and size.


March 4, 2013, 21:52 

#7 
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sajeesh
Join Date: Feb 2013
Posts: 52
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i tried but its not working............you r right sir...the key area is the time step....actually how the iteration is done...iterating the fluid in a certain number.then injecting the particle ..the particle advancing time period how we can determined..when the DPM iteration is happening...i have no idea from the guide....pls help me sir...regarding the iteration procedure
thanks 

March 5, 2013, 12:51 

#8 
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AA Azarafza
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You need to get a converged solution without DPM model, then inject the particles. There are several types of particle injecting. You can inject only one particle or a group of particles or other types described in user guide. You can even adjust RosinRamler parametrs and use this method. Hope it help.


March 5, 2013, 23:18 

#9 
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sajeesh
Join Date: Feb 2013
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sir one more doubt..if i want one particle to track..how i put one particle in one stream..option single in injection means that single stream.that is not one particle.sir what value i should give to the mass flow rate for one particle.and initially i want to place the particle not with one velocity at the injection point.can i set a velocity of zero for a stationary particle at the inlet.
sorry sir if it is blunder thank a lot for your reply 

March 6, 2013, 12:34 

#10 
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AA Azarafza
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I think what you need is injecting massless particle. In this case you don't need to set velocity value or even mass flow rate. The only thing would be required is the position of the injected particle. Actually, in this method of injecting the particles move along the stream lines.
Good Luck 

March 6, 2013, 12:48 

#11 
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AA Azarafza
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Please If you have any questions, contact me as:
aboozar.azarafza@gmail.com Cause, I may forget to see this page. 

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