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

Rocket nozzle simulation , simulation time

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 13, 2015, 03:09
Default Rocket nozzle simulation , simulation time
  #1
Member
 
Hilbert
Join Date: Aug 2015
Location: Australia
Posts: 50
Rep Power: 10
Hillie is on a distinguished road
Dear Foamers,

I have been working on rocket nozzle simulations, and after some effort got them to work. (once have a comparison with my current commercial code CFX i will post a reference here)

I use coarse mesh to get a initial result, then map that solution to a fine mesh, on which i generate my final result.

What I have noticed is that when I use mapFields to map my coarse mesh to my fine mesh I get oscillations/steps in the mapped solution. And certainly in the subsonic region of the rocket nozzle it takes a while to get rid of those using the compressible solvers.

I was therefore wondering if anybody has an suggestion/experience with a smoother that i can use to smooth out my solution on the fine grid before i start iterating on my fine grid?
Hillie is offline   Reply With Quote

Old   October 13, 2015, 09:25
Default
  #2
Senior Member
 
Vincent RIVOLA
Join Date: Mar 2009
Location: France
Posts: 283
Rep Power: 18
vinz is on a distinguished road
Hi,

Which solver do you use for your nozzle simulations?
Are they steady state or transient?

In MapFields you have different methods to make the mapping:
- cellVolumeWeight
- direct
- mapNearest

Did you try all of them? Maybe one is better than the others for your case.
vinz is offline   Reply With Quote

Old   October 15, 2015, 21:59
Default
  #3
Member
 
Hilbert
Join Date: Aug 2015
Location: Australia
Posts: 50
Rep Power: 10
Hillie is on a distinguished road
thanks for your reply.

I know mapfields has different mapping options. The 2 non default ones did work. (there was an error in one, and the other had a non-physical result.)

I am currently working with the transient solvers. Correct me if i am wrong here, but the steady state compressible solvers aren’t set up with hyperbolic equations and therefore cannot handle supersonic flow? (If you do know of a good steady state supersonic solver I am all ears).

What I currently do is run the startup simulation with sonicFoam, and run the dense mesh with rhoCentralFoam
Hillie is offline   Reply With Quote

Old   October 16, 2015, 03:21
Default
  #4
Senior Member
 
Vincent RIVOLA
Join Date: Mar 2009
Location: France
Posts: 283
Rep Power: 18
vinz is on a distinguished road
Hi,

You may want to try the dbnsFoam (or dbnsTurbFoam) solvers available in foam-extend.
They are supposed to do a better job for supersonic flows.
vinz 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
How to export time series of variables for one point? mary mor OpenFOAM Post-Processing 8 July 19, 2017 11:54
Extrusion with OpenFoam problem No. Iterations 0 Lord Kelvin OpenFOAM Running, Solving & CFD 8 March 28, 2016 12:08
simpleFoam error - "Floating point exception" mbcx4jc2 OpenFOAM Running, Solving & CFD 12 August 4, 2015 03:20
Need help with a rocket nozzle simulation badboyz31 CFX 14 September 22, 2014 01:06
Star cd es-ice solver error ernarasimman STAR-CD 2 September 12, 2014 01:01


All times are GMT -4. The time now is 03:52.