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

Group DPM injection - pathline convergence

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 4, 2019, 14:20
Default Group DPM injection - pathline convergence
  #1
New Member
 
Amy M
Join Date: Feb 2019
Posts: 3
Rep Power: 4
A_Keen is on a distinguished road
Hello everyone,

I'm somewhat new to FLUENT and have been using a steady state, massless dpm group injection in a 2D axisymmetric, laminar (Re < 7 in my whole domain), steady simulation. My issue is that my resultant pathlines overlap in the "Poiseuille flow" region, and I don't understand why they seem to bunch up.

The left borders are inlets, the right an outlet, the bottom is the axisymmetric boundary and the rest are walls:

The underlying mesh is largely quad with inflation at the walls. At the inlet (left side) there is ~55 cells in the y-direction.


I have exported the position information from the simulation for post-processing in Matlab. I have tried injecting many different numbers of particles (15 - 500) along the line x=.002 m. When I plot the 300 pathline case, it looks like the following example:

Zooming in on a smaller region looks like this:



Evidently, the pathlines start in independent regions but they end up with a spacing smaller than a micron.

Looking at the number of discrete regions where the pathlines end, it is greater than the number of cells across, so it doesn't seem to me like the limitation is directly mesh-related. From my understanding, I thought interpolation was done between the different cell points to propagate the particle, so I didn't expect these groups to bunch up so much. Also, when I look at streamlines in CFD-Post this behaviour does not occur. The streamlines remain straight in this region without "bunching up", as I expected. From my understanding, a steady laminar simulation of massless DPM should be equivalent to streamlines, so why is this not the case? Have I misunderstood?

Question summary: How does the massless DPM work such that it is causing this phenomena?

Thanks for the help
A_Keen is offline   Reply With Quote

Reply

Tags
dpm in fluent, pathline distribution

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
file injection.: continuity fail; volume injection.: wrong total mass blerli_91 Fluent Multiphase 6 October 2, 2018 05:34
Dense DPM Injection Help (basic sedimentation) sgelman FLUENT 0 July 21, 2010 14:19
Two-Phase Buoyant Flow Issue Miguel Baritto CFX 4 August 31, 2006 12:02
about group injection of DPM model zwdi FLUENT 5 April 12, 2004 19:31
DPM Injection Parameters Hendawi FLUENT 0 June 13, 2002 09:41


All times are GMT -4. The time now is 17:57.