CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLOW-3D

Problem with Baffle output "sediment flow rate"

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 7, 2017, 10:38
Default Problem with Baffle output "sediment flow rate"
  #1
Member
 
Chris
Join Date: Jun 2014
Posts: 39
Rep Power: 5
chripasch is on a distinguished road
Sponsored Links
Dear experts,
I am doing some more or less basic investigations and just observed a strange issue: I am modeling a straight channel of 0.5 m width, about 30 m length and a packed sediment bed of about 0.3 m thickness. In the last third of the channel a trench is located (actually, this is the migrating trench experiment of van Rijn). The sediment has a diameter of 160 microns and a density of 2650 kg/s. The first 5 meters of the domain have a fixed bed. The initial condition is shown in Figure one names "T=0".

On purpose, I chose parameters yielding massive erosion of the sediment, such that nearly all sediment got eroded after 500 seconds simulation time, see Figure "T=500". Checking the output of the baffles I added at several positions (e.g. 5 meters upstream of the channel end) gives sediment transport rates of about zero. I added Figure "TransportedSedimentMass" to show you the problem: The left column is the time, the right column the cumulated transported sediment mass (!) until the end of the simulation at 500 s. As you can see, following the baffle output, less than 0.2 kg have passed that baffle, although nearly ALL sediment was eroded (the total mass in the domain is about 5'000 kg).

Did you experience such problems as well? Do I misinterpret the output? What is wrong over here?

Thanks a lot for your help in advance. I very appreciate it!
Chris
Attached Images
File Type: png T=0.PNG (49.8 KB, 16 views)
File Type: png T=500.PNG (59.8 KB, 15 views)
File Type: png TransportedSedimentMass.PNG (22.7 KB, 14 views)
chripasch is offline   Reply With Quote
Sponsored Links

Old   March 10, 2017, 13:44
Default
  #2
New Member
 
brian
Join Date: Apr 2012
Posts: 22
Blog Entries: 1
Rep Power: 7
bfox48 is on a distinguished road
The baffle output is the baffle suspended sediment flow rate through the baffle.
bfox48 is offline   Reply With Quote

Old   March 13, 2017, 01:13
Default
  #3
Member
 
Chris
Join Date: Jun 2014
Posts: 39
Rep Power: 5
chripasch is on a distinguished road
Thanks, this information clarifies the issue and helps me quite a lot!

Connecting question: How is the output "mass of packed sediment species x" (x stands for the number of the corresponding species) determined by the software? I am missing some information here to interpret my results.
Thanks a lot in advance!

Last edited by chripasch; March 13, 2017 at 09:49.
chripasch is offline   Reply With Quote

Old   March 13, 2017, 09:49
Default
  #4
Member
 
Chris
Join Date: Jun 2014
Posts: 39
Rep Power: 5
chripasch is on a distinguished road
Connecting question: How is the output "mass of packed sediment species x" (x stands for the number of the corresponding species) determined by the software? I am missing some information here to interpret my results.
Thanks a lot in advance!
chripasch is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Problem with porous flow at multi-material interface with large permeability diff. Hisham OpenFOAM Programming & Development 1 June 3, 2016 10:51
Newbie to compressible, viscous flow. Advice on approach to problem? bzz77 Main CFD Forum 4 December 4, 2012 08:59
flow past abdominal aorta. Complex BC problem. ziemowitzima OpenFOAM Running, Solving & CFD 0 April 5, 2010 13:30
Multiphase flow problem icedou FLUENT 6 July 10, 2005 02:52
Periodic flow boundary condition problem sudha FLUENT 3 April 28, 2004 08:40

Sponsored Links


All times are GMT -4. The time now is 00:18.