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

Obtaining negative temperature sonicFoam

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 22, 2019, 07:47
Default Obtaining negative temperature sonicFoam
  #1
New Member
 
adrian chelaru
Join Date: Mar 2015
Posts: 4
Rep Power: 9
chelucupar is on a distinguished road
Hello!
I am trying to simulate a Naca0012 profile, using the sonicFoam solver.
My trouble is that I am obtaining a negative temperature and the solver crashes. Also, if I plot the residuals, the continuity equation shows negative values. Anyone has any ideas? I saw some posts with similar problems, but no result was found what so ever.
I am also having troubles with setting my boundaries conditions. I am new in openFoam. My trouble is, what kind of boundary conditions should I set if I want to have a farfield like in Fluent?
chelucupar is offline   Reply With Quote

Old   May 24, 2019, 01:53
Default tutorial case?
  #2
Senior Member
 
Will Kernkamp
Join Date: Jun 2014
Posts: 170
Rep Power: 10
wkernkamp is on a distinguished road
I usually start from a tutorial case. For sonicFoam look in compressible.
wkernkamp is offline   Reply With Quote

Old   July 17, 2019, 15:58
Lightbulb Try and control cfl number using adjustable time step feature in OF
  #3
New Member
 
Dumbledore
Join Date: Jun 2019
Posts: 10
Rep Power: 5
hemanthgrylls is on a distinguished road
https://www.cfd-online.com/Forums/op....html#poststop

check this out

Increase in courant number maybe the reason for blowup

A same time step through out the simulation is not suitable

During some iterations the demand for time step is very less due to flow characteristics in the domain and non robustness of the solver.

so try to enable "adjustabletimestep" in controldict which can control time step and controls the steady increase in courant number

add this lines in your controldict code:

HTML Code:
adjustTimeStep  yes;

maxCo               0.7;

maxDeltaT          0.01;

You can also limit the degree of temperature value update after every iteration using relaxation factor for you energy equation.

HTML Code:
relaxationFactors 
  { 
      fields
      { 
          p                           0.3; 
          T 			       0.3;
      } 
      equations 
      { 
         U                            0.4; 
        "(rho|k|nuTilda|e).*" 0.4; 
      } 
  }  
hemanthgrylls is offline   Reply With Quote

Old   July 17, 2019, 16:04
Default
  #4
New Member
 
Dumbledore
Join Date: Jun 2019
Posts: 10
Rep Power: 5
hemanthgrylls is on a distinguished road
https://www.openfoam.com/documentati...conditions.php


http://www.nextfoam.co.kr/lib/downlo...bb43ccfe025b25

Please go through these links and these might help you as a reference when you while you are stuck in defining boundary conditions.
hemanthgrylls is offline   Reply With Quote

Reply

Tags
negative temperature, openfoam., sonicfoam

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
Negative temperature and pressure in sonicFoam :O gallon OpenFOAM Running, Solving & CFD 16 January 21, 2019 06:56
[blockMesh] error message with modeling a cube with a hold at the center hsingtzu OpenFOAM Meshing & Mesh Conversion 2 March 14, 2012 10:56
Unexpected large decrease in Total temperature across the shock using sonicFoam JLight OpenFOAM 0 December 16, 2010 12:46
Unexpected large decrease in Total temperature across the shock using sonicFoam JLight OpenFOAM Running, Solving & CFD 0 December 15, 2010 06:47
[blockMesh] Axisymmetrical mesh Rasmus Gjesing (Gjesing) OpenFOAM Meshing & Mesh Conversion 10 April 2, 2007 15:00


All times are GMT -4. The time now is 17:33.