CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Unrealistic results using DPMFoam

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

Like Tree1Likes
  • 1 Post By maysmech

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 14, 2015, 14:28
Default Unrealistic results using DPMFoam
  #1
Senior Member
 
Mojtaba.a's Avatar
 
Mojtaba Amiraslanpour
Join Date: Jun 2011
Location: Tampa, US
Posts: 308
Rep Power: 16
Mojtaba.a is on a distinguished road
Send a message via Skype™ to Mojtaba.a
Hi,

I am rather new to DPMFoam. I wanted to simulate a very simple T-Junction problem, in which there is one inlet and two outlets.

You can see the images. The first image is done using icoFoam, and there is no problem in here.



The second image is using DPMFoam, I have disabled the coupling between the continuous phase and particles.



I am focusing on the continuous phase. But I can not get the results obtained previously by icoFoam.

What am I doing wrong?

You can get the DPM case from the link below:

https://www.dropbox.com/s/726lc9bdt3...PM.tar.gz?dl=0


Thanks,
Mojtaba.
Attached Images
File Type: png icoFoam.png (10.8 KB, 124 views)
File Type: png DPM.png (10.9 KB, 125 views)
__________________
Learn OpenFOAM in Persian
SFO (StarCCM+ FLUENT OpenFOAM) Project Team Member
Complex Heat & Flow Simulation Research Group
If you can't explain it simply, you don't understand it well enough. "Richard Feynman"
Mojtaba.a is offline   Reply With Quote

Old   January 22, 2015, 15:06
Default
  #2
Senior Member
 
Mojtaba.a's Avatar
 
Mojtaba Amiraslanpour
Join Date: Jun 2011
Location: Tampa, US
Posts: 308
Rep Power: 16
Mojtaba.a is on a distinguished road
Send a message via Skype™ to Mojtaba.a
Are there any suggestions ?!

I just want to make similar results to icoFoam using DPMFoam in which I have disabled all particle forces.
I am trying to first validate the results obtained by solving fluid equations and then solving for particles.

I would really appreciate if somebody could help.
Thanks.
__________________
Learn OpenFOAM in Persian
SFO (StarCCM+ FLUENT OpenFOAM) Project Team Member
Complex Heat & Flow Simulation Research Group
If you can't explain it simply, you don't understand it well enough. "Richard Feynman"
Mojtaba.a is offline   Reply With Quote

Old   January 24, 2015, 03:52
Default
  #3
Senior Member
 
maysmech's Avatar
 
Join Date: Jan 2010
Posts: 347
Blog Entries: 2
Rep Power: 17
maysmech is on a distinguished road
Quote:
Originally Posted by Mojtaba.a View Post
Are there any suggestions ?!

I just want to make similar results to icoFoam using DPMFoam in which I have disabled all particle forces.
I am trying to first validate the results obtained by solving fluid equations and then solving for particles.

I would really appreciate if somebody could help.
Thanks.
Hi,
Check the kinematic viscosity and density of fluid phase.
The reason behind the unrealistic result is gravity effect on fluid. When I turned off the gravity the result was ok, so it is because of 1) small inlet velocity magnitude, 2) viscous and dense fluid phase
You didn't send the icoFoam case but I think you used air properties there and are using something like water properties here.
maysmech is offline   Reply With Quote

Old   January 24, 2015, 04:40
Default
  #4
Senior Member
 
Mojtaba.a's Avatar
 
Mojtaba Amiraslanpour
Join Date: Jun 2011
Location: Tampa, US
Posts: 308
Rep Power: 16
Mojtaba.a is on a distinguished road
Send a message via Skype™ to Mojtaba.a
Quote:
Originally Posted by maysmech View Post
Hi,
Check the kinematic viscosity and density of fluid phase.
The reason behind the unrealistic result is gravity effect on fluid. When I turned off the gravity the result was ok, so it is because of 1) small inlet velocity magnitude, 2) viscous and dense fluid phase
You didn't send the icoFoam case but I think you used air properties there and are using something like water properties here.
Thank you for your fast response.

Well, you were right. All I wanted to do was to disable gravity. I am getting nice results now.

Regarding the kinematic viscosity and density of the fluid, I am not using air nor water properties for my simulation. Actually I am trying to simulate a very viscous fluid.

There is another question I have. By disabling gravity I have disabled the weight force induced on both fluid and particles. How can I include the weight force on particles and not on the fluid phase?

Thank you,
Best.
__________________
Learn OpenFOAM in Persian
SFO (StarCCM+ FLUENT OpenFOAM) Project Team Member
Complex Heat & Flow Simulation Research Group
If you can't explain it simply, you don't understand it well enough. "Richard Feynman"
Mojtaba.a is offline   Reply With Quote

Old   January 24, 2015, 11:28
Default
  #5
Senior Member
 
maysmech's Avatar
 
Join Date: Jan 2010
Posts: 347
Blog Entries: 2
Rep Power: 17
maysmech is on a distinguished road
Quote:
Originally Posted by Mojtaba.a View Post
Thank you for your fast response.

Well, you were right. All I wanted to do was to disable gravity. I am getting nice results now.
I didn't suggest to turn off gravity to reach true answer. It was a trick to find the source of difference between icoFoam and DPMFoam results. So If you want compare both solvers you need to use similar properties, especially the density.
Mojtaba.a likes this.
maysmech is offline   Reply With Quote

Reply

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
OpenFOAM - Validation of Results Ahmed OpenFOAM Running, Solving & CFD 10 May 13, 2018 19:28
Oscillating Airfoil Poor Results at High k (reduced frequency) dancfd OpenFOAM Running, Solving & CFD 3 November 4, 2013 09:32
CFD results not close to experimental results cider STAR-CCM+ 0 July 8, 2013 08:53
Creating a tool to interpolate results Luis Batista OpenFOAM Running, Solving & CFD 2 April 11, 2013 09:15
CFX cylinder or sphere benchmark results Mel CFX 1 August 8, 2005 19:47


All times are GMT -4. The time now is 07:11.