CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

"DDPM"; "dense gas-solid flow" Question About Particle Number in Parcel

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree1Likes
  • 1 Post By hcs129

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 1, 2017, 00:45
Default "DDPM"; "dense gas-solid flow" Question About Particle Number in Parcel
  #1
New Member
 
Hu
Join Date: Jan 2014
Posts: 22
Rep Power: 12
hcs129 is on a distinguished road
Hi everybody
Happy new year
I have a question about the ANSYS tutorial, "Modeling bubbling fluidized bed using DDPM+DEM".
In the tutorial 92,000 parcel are initialized in the bed, with 127 particles in each parcel. As I try to decrease the particle number in parcel, injection duration is decreased from 10e-8 to 10e-10. As a result, each parcel has only 1.27 particle. It cause a totally different gas-solid behavior compared to 127 particles per parcel.
With 127 particles per parcel, bubbling fluidized regime are formed as shown in 1.jpg.
While for 1.27 particle per parcel, particles are blown up to top region and distribute uniformly in the whole box, as shown in 2.png.
To my understanding, they have same particle properties such as particle diameter and density. The particle distributions of them should not differ with each other so obviously.
I have also tried 12.7 particle per parcel. It is similar to the 127 particles percel.
So how to give a proper particle number per parcel and why 1.27 particle per parcel will lead to a unrealistic result.
Any one can help?
C.Hu
Attached Images
File Type: jpg 1.jpg (49.8 KB, 27 views)
File Type: png 2.png (22.1 KB, 25 views)
ronithstanly likes this.
hcs129 is offline   Reply With Quote

Old   July 13, 2017, 01:27
Smile Solution for solving erroneous flying parcels in DDPM DEM Fluent
  #2
New Member
 
Ronith Stanly
Join Date: Mar 2017
Location: Sweden
Posts: 24
Rep Power: 9
ronithstanly is on a distinguished road
I too had the same issue (but not with the same problem statement, but a very close one), you should change the parcel diameter when changing the number of particles contained within the parcel-because in DEM the volume should be conserved (See Page 3: https://mfix.netl.doe.gov/download/m...ix_pic_doc.pdf ). Here, in this case, since you are decreasing the number of particles, the diameter should be decreased by the cube root of the initial diameter (to conserve volume of spheres).

In my case, I also had to change the spring constant of the parcels to get a volume fraction distribution similar to my TFM simulation (Because since the experiment of Kuipers 1992 found in the literature did not mention the spring constant of the glass beads they used, so I initially made a wild guess of k=1000 and that sent the parcels flying to space , then I changed to k=100 and it gave realistic flowfields).

This reply might be a bit late, but I will be glad if this helps you or anyone else who encounters the same problem.
ronithstanly is offline   Reply With Quote

Old   April 22, 2022, 05:52
Default
  #3
New Member
 
hossein
Join Date: Oct 2021
Posts: 12
Rep Power: 5
hossein76 is on a distinguished road
Hi, I want to do a 4-way coupling in Fluent. Can you help me? Thank you (dem-ddpm)
h.mrad13766@gmail.com
hossein76 is offline   Reply With Quote

Old   April 22, 2022, 05:53
Default
  #4
New Member
 
hossein
Join Date: Oct 2021
Posts: 12
Rep Power: 5
hossein76 is on a distinguished road
Quote:
Originally Posted by ronithstanly View Post
I too had the same issue (but not with the same problem statement, but a very close one), you should change the parcel diameter when changing the number of particles contained within the parcel-because in DEM the volume should be conserved (See Page 3: https://mfix.netl.doe.gov/download/m...ix_pic_doc.pdf ). Here, in this case, since you are decreasing the number of particles, the diameter should be decreased by the cube root of the initial diameter (to conserve volume of spheres).

In my case, I also had to change the spring constant of the parcels to get a volume fraction distribution similar to my TFM simulation (Because since the experiment of Kuipers 1992 found in the literature did not mention the spring constant of the glass beads they used, so I initially made a wild guess of k=1000 and that sent the parcels flying to space , then I changed to k=100 and it gave realistic flowfields).

This reply might be a bit late, but I will be glad if this helps you or anyone else who encounters the same problem.
Hi, I want to do a 4-way coupling in Fluent. Can you help me? Thank you (dem-ddpm)
h.mrad13766@gmail.com
hossein76 is offline   Reply With Quote

Reply

Tags
ddpm, fluidized bed, multiphase flow

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
decomposePar no field transfert Jeanp OpenFOAM Pre-Processing 3 June 18, 2022 13:01
DPMFoam - Serious Error --particle-laden flow in simple geometric config benz25 OpenFOAM Running, Solving & CFD 27 December 19, 2017 21:47
AMI interDyMFoam for mixer danny123 OpenFOAM Running, Solving & CFD 4 June 19, 2013 05:49
Gas pressure question Dan Moskal Main CFD Forum 0 October 24, 2002 23:02
CFX4.3 -build analysis form Chie Min CFX 5 July 13, 2001 00:19


All times are GMT -4. The time now is 01:36.