unsteady DPM and steady flow

Mohsin · August 18, 2010, 05:16

I have unsteady DPM and steady flow but after 4000 iterations when solution converges. The particle fate is empty. I cant see any particle tracked. why it is so. Please explain.

xrs333 · August 18, 2010, 05:44

Hi,
Is the number that follows 'tracked=' reported in the console zero, too?

Mohsin · August 18, 2010, 05:45

hi

No. its not. Its just not displaying any number. only writing fate and mass flux labels.

thanks

xrs333 · August 18, 2010, 06:09

Hi, Mohsin,
Have you set petinent start time and stop time for the injection?

Mohsin · August 18, 2010, 06:15

It is steady state for the air flow but for DPM the particles will enter into the domain at t=8 seconds and will be injected until t=16 seconds. so i gave the particle strat andend time as 8 to 16 respetively.

The time step size was given as =0.5
and total number of time steps was=50

because the particles are large so i though to give the step size as 0.5 (which means after every 0.5 seconds the assigned number of particles will be injected) and the time period for the particles to stay in the domain was 5 seconds in steady case so 0.5/5=10 gives me the number of time steps for 1 period (i-e when the particles will move from inlet and captured at the outlet) so then i assumed 50 total number of time steps for my case so that i could simulate for 5 periods.

What could be wrong?

xrs333 · August 18, 2010, 06:22

I think all the particles injected during t=8~16s have escaped from the domain after some time steps of iteration.

souria · October 9, 2014, 06:30

Hey Mohsin,
What did you call by "Period" here ?? And what does represent "5s" ? I m in the same case as you, and Im tryning to undersatnd the meaning of each parameters (number time step, particle time step size, start time, stop time..)

August 18, 2010, 05:16	unsteady DPM and steady flow	#1
Mohsin Senior Member Mohsin Mukhtar Join Date: Mar 2010 Location: South Korea Posts: 249 Rep Power: 17	I have unsteady DPM and steady flow but after 4000 iterations when solution converges. The particle fate is empty. I cant see any particle tracked. why it is so. Please explain.

October 9, 2014, 06:30		#7
souria Member souria Join Date: Mar 2013 Location: Nancy Posts: 66 Rep Power: 13	Hey Mohsin, What did you call by "Period" here ?? And what does represent "5s" ? I m in the same case as you, and Im tryning to undersatnd the meaning of each parameters (number time step, particle time step size, start time, stop time..) sharonyue likes this.

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August 18, 2010, 05:44		#2
xrs333 Senior Member xrs333 Join Date: Aug 2010 Posts: 125 Rep Power: 17	Hi, Is the number that follows 'tracked=' reported in the console zero, too?

August 18, 2010, 05:45		#3
Mohsin Senior Member Mohsin Mukhtar Join Date: Mar 2010 Location: South Korea Posts: 249 Rep Power: 17	hi No. its not. Its just not displaying any number. only writing fate and mass flux labels. thanks

August 18, 2010, 06:09		#4
xrs333 Senior Member xrs333 Join Date: Aug 2010 Posts: 125 Rep Power: 17	Hi, Mohsin, Have you set petinent start time and stop time for the injection?

August 18, 2010, 06:15		#5
Mohsin Senior Member Mohsin Mukhtar Join Date: Mar 2010 Location: South Korea Posts: 249 Rep Power: 17	It is steady state for the air flow but for DPM the particles will enter into the domain at t=8 seconds and will be injected until t=16 seconds. so i gave the particle strat andend time as 8 to 16 respetively. The time step size was given as =0.5 and total number of time steps was=50 because the particles are large so i though to give the step size as 0.5 (which means after every 0.5 seconds the assigned number of particles will be injected) and the time period for the particles to stay in the domain was 5 seconds in steady case so 0.5/5=10 gives me the number of time steps for 1 period (i-e when the particles will move from inlet and captured at the outlet) so then i assumed 50 total number of time steps for my case so that i could simulate for 5 periods. What could be wrong?

August 18, 2010, 06:22		#6
xrs333 Senior Member xrs333 Join Date: Aug 2010 Posts: 125 Rep Power: 17	I think all the particles injected during t=8~16s have escaped from the domain after some time steps of iteration.