|
[Sponsors] |
March 7, 2018, 04:23 |
unusual behavior with DEM-CFD
|
#1 |
New Member
george bergantz
Join Date: Mar 2009
Location: Seattle, Washington, USA
Posts: 9
Rep Power: 17 |
When we do a simple DEM particle settling run in a closed box with no fluid (granular only) it works just fine. However when we do that same run with a fluid, once the particles have settled they start "hopping" and moving in a non-physical manner even when there is no other fluid motion, the fluid should be static.
Has anyone else encountered this bizarre behavior? Thanks |
|
March 8, 2018, 04:17 |
|
#2 |
Senior Member
|
What do you mean by particles are settled. Does is mean that they are settled on the wall or hanging in domain. And what is desired physical behavior you are looking for ?
|
|
March 8, 2018, 11:49 |
|
#3 |
New Member
george bergantz
Join Date: Mar 2009
Location: Seattle, Washington, USA
Posts: 9
Rep Power: 17 |
By settled I mean sedimentation to the floor. Think of simple spherical particles settling under gravity. Once they are resting on the floor no more motion should occur. And the fluid velocity should go to zero. However what I find is that once the particles are resting on the floor some randomly start to suddenly rise a short distance, maybe 5 particle diameters, then fall back down. This is obviously non-physical. Sometimes the whole particle bed will start to do this.
Has anyone else encountered this? |
|
March 9, 2018, 01:57 |
|
#4 | |
Senior Member
|
Quote:
|
||
March 9, 2018, 02:14 |
|
#5 |
New Member
george bergantz
Join Date: Mar 2009
Location: Seattle, Washington, USA
Posts: 9
Rep Power: 17 |
Thank you, but consider this, if one does the DEM run under granular conditions, heer there is no fluid, the non-physical behavior does not occur. Particles settle and remain as they should without artificially forcing them to stick. So something in the fluid-particle interaction produces a non-physical force imbalance that makes the particles rise up- even those that are not in direct contact with the floor but are resting on other particles.
|
|
March 9, 2018, 03:33 |
|
#6 | |
Senior Member
|
Quote:
|
||
May 15, 2018, 15:01 |
|
#7 | |
Member
Casey
Join Date: Jun 2009
Posts: 98
Rep Power: 17 |
Quote:
|
||
Tags |
dem, dem-cfd, multiphase |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
CFD Online Celebrates 20 Years Online | jola | Site News & Announcements | 22 | January 31, 2015 01:30 |
Where do we go from here? CFD in 2001 | John C. Chien | Main CFD Forum | 36 | January 24, 2001 22:10 |
ASME CFD Symposium, Atlanta, July 2001 | Chris R. Kleijn | Main CFD Forum | 0 | August 21, 2000 05:49 |
Which is better to develop in-house CFD code or to buy a available CFD package. | Tareq Al-shaalan | Main CFD Forum | 10 | June 13, 1999 00:27 |
public CFD Code development | Heinz Wilkening | Main CFD Forum | 38 | March 5, 1999 12:44 |