Pressure drop due to particle injection

semo · September 9, 2014, 17:26

I am trying to model the pressure drop resulting from solid particle injection to the air/gas stream. There should be a pressure drop from solids entering to the domain since their speed is increased from almost zero to stream velocity. Probably from 1 ft/sec to 100 ft/sec.

I can model the pressure drop by adding a dummy porous zone or just calculating it manually but I am just wondering if this is even possible with Fluent.

I tried this with DPM without interaction with the continuous phase. When I tried it with the interaction, solution diverges.

Any suggestions?

karimnejad · September 10, 2014, 06:03

Hi semo. I don't know if my answer is useful or not but I had some problem with diverging DPM with interaction too.

my geometry was a tub which the particles injected perpendicular to flow streams and as my boundary condition was pressure inlet with 21 bar gage pressure,when I ticked the "interaction" my solution diverged.

I found out with trial and error that when you solve the problem with a relatively less pressure inlet but with interaction and little by little increasing the pressure from boundary condition, the solution don't diverge.

also solving the DPM in transient could help even if your problem is steady.
use first order schemes for start and small under relaxation factors.

I hope this could help.

semo · September 11, 2014, 15:12

thank you for the response. I already tried that so I guess maybe I need a finer mesh.

by the way my inlet is a velocity inlet so I increased the inlet velocity and also the particle loading (kg/sec) gradually. I reduced the URFs as well. The mesh looks ok too as all of them are hex cells and good quality.

thanks again.

September 9, 2014, 17:26	Pressure drop due to particle injection	#1
semo Member Join Date: Jun 2010 Posts: 31 Rep Power: 16	I am trying to model the pressure drop resulting from solid particle injection to the air/gas stream. There should be a pressure drop from solids entering to the domain since their speed is increased from almost zero to stream velocity. Probably from 1 ft/sec to 100 ft/sec. I can model the pressure drop by adding a dummy porous zone or just calculating it manually but I am just wondering if this is even possible with Fluent. I tried this with DPM without interaction with the continuous phase. When I tried it with the interaction, solution diverges. Any suggestions?

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September 10, 2014, 06:03		#2
karimnejad New Member Ali Join Date: Jan 2014 Posts: 5 Rep Power: 12	Hi semo. I don't know if my answer is useful or not but I had some problem with diverging DPM with interaction too. my geometry was a tub which the particles injected perpendicular to flow streams and as my boundary condition was pressure inlet with 21 bar gage pressure,when I ticked the "interaction" my solution diverged. I found out with trial and error that when you solve the problem with a relatively less pressure inlet but with interaction and little by little increasing the pressure from boundary condition, the solution don't diverge. also solving the DPM in transient could help even if your problem is steady. use first order schemes for start and small under relaxation factors. I hope this could help.

September 11, 2014, 15:12		#3
semo Member Join Date: Jun 2010 Posts: 31 Rep Power: 16	thank you for the response. I already tried that so I guess maybe I need a finer mesh. by the way my inlet is a velocity inlet so I increased the inlet velocity and also the particle loading (kg/sec) gradually. I reduced the URFs as well. The mesh looks ok too as all of them are hex cells and good quality. thanks again.