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

Helium jet instability using reactingFoam

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 18, 2017, 05:04
Default Helium jet instability using reactingFoam
  #1
New Member
 
Anshul Lakhani
Join Date: Jun 2015
Posts: 6
Rep Power: 6
Assasin is on a distinguished road
Hello Foamers,

i am new to openfoam so kindly excuse my lack of knowledge.

i am trying to simulate a helium jet being fired into ambient using reactingfoam with chemistry and combustion switched off. Helium jets being significantly lighter than air are unstable and oscillate at a fixed frequency (like flow past a cylinder). A screenshot of the flow field showing the helium concentration is attached. (geometry is 2D- one cell in z direction).
To measure this frequency i am using a pressure probe at 3D location (D is diameter of inlet). what i expect from the pressure probe is that after the initial transients it would show a constant amplitude sinusoidal pressure signal, that is not the case ofcourse.

Even if i run the simulation for a long time, the jet doesnt seem to settle down (to uniform oscillations).
The reynolds number based on diameter is 1800 and it is run as a laminar case.
i have tried reducing the reynolds number, delta T, still the situation doesnt improve.
Although since it is PIMPLE algorithm, increasing the number of outer iterations improved the signal, but not to the desired level. the case files are also attached, kindly take a look and let me know what can be done.

Thank you,
Anshul
Attached Images
File Type: jpg Screenshot from 2017-01-18 14-06-29.jpg (94.9 KB, 45 views)
File Type: jpg pressuresignal.jpg (61.5 KB, 24 views)
Attached Files
File Type: zip polyMesh1.zip (179.1 KB, 15 views)
File Type: zip polyMesh2.zip (77.0 KB, 13 views)
File Type: zip casefiles.zip (10.5 KB, 30 views)
Assasin is offline   Reply With Quote

Reply

Tags
instability, laminarjet, openfoam, reactingfoam

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
Supersonic helium jet with sonicFoam Intrepid OpenFOAM Pre-Processing 7 May 1, 2019 23:04
2D Plane Jet Fluent Solution doug Main CFD Forum 11 February 4, 2019 10:34
Low density Jet Instability Assasin Main CFD Forum 5 February 24, 2016 07:29
"Hand" calculation jet fan in the garage mageno Main CFD Forum 2 October 27, 2015 01:48
Jet in Supersonic Crossflow, controlling mass flow rate ChrisA OpenFOAM Running, Solving & CFD 3 November 13, 2012 19:20


All times are GMT -4. The time now is 05:58.