CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > SU2

Simulation of hypersonic flow: NaN in the residual

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 26, 2015, 00:43
Default Simulation of hypersonic flow: NaN in the residual
  #1
New Member
 
David Hwang
Join Date: Feb 2014
Posts: 5
Rep Power: 12
smanist is on a distinguished road
Hi guys,

I have just begun using SU2, which I hope I can use to simulate hypersonic flow with real gas effects. I assumed that is possible, because I noticed the existence of TNE2 module in SU2. I have tried the RAMC-II test case and ran a Mach 12 double-wedge airfoil case for Euler solution. They worked well.

However, when I try to get RANS solution of the double-wedge case, I get this error
Code:
------------------------------ Begin Solver -----------------------------

!!! Error: There is a NaN in the residual. Now exiting... !!!
In my case, I configured flow condition to be H=12km in atmosphere,
Code:
FREESTREAM_TEMPERATURE= 220.61
REYNOLDS_NUMBER= 8.07145E7
REYNOLDS_LENGTH= 1.0
The output of SU2 is correct, as it shows
Code:
Specific gas constant: 287.058 N.m/kg.K.
Free-stream pressure: 20646.1 Pa.
Free-stream temperature: 220.61 K.
Free-stream density: 0.326019 kg/m^3.
Free-stream velocity: (3573.08, 0) m/s. Magnitude: 3573.08 m/s.
Free-stream total energy per unit mass: 6.54177e+06 m^2/s^2.
Free-stream viscosity: 1.44323e-05 N.s/m^2.
For the rest of the configure file, the key settings are, (the whole file is just too long to be posted here)
Code:
PHYSICAL_PROBLEM= NAVIER_STOKES
KIND_TURB_MODEL= SA
VISCOSITY_MODEL= SUTHERLAND
MARKER_HEATFLUX= ( UPPER, 0.0, LOWER, 0.0 ) % Wall BC
MARKER_FAR= ( INLET, OUTLET ) % Farfield
CONV_NUM_METHOD_FLOW= ROE
SPATIAL_ORDER_FLOW= 2ND_ORDER
SLOPE_LIMITER_FLOW= VENKATAKRISHNAN
TIME_DISCRE_FLOW= EULER_IMPLICIT
CONV_NUM_METHOD_TURB= SCALAR_UPWIND
SPATIAL_ORDER_TURB= 2ND_ORDER
SLOPE_LIMITER_TURB= VENKATAKRISHNAN
TIME_DISCRE_TURB= EULER_IMPLICIT
I also tried Mach 2 (Re=1.34524E7), after several iterations, same issue happens. For Mach 3 (Re=2.01786E7), same thing, except that there is also a message,
Code:
There are 4 non-physical states in the upwind reconstruction.
I am still playing with the setting to see what happens. Any idea what might be wrong here? Any help will be appreciated.

Thank you in advance!
Danny

Last edited by smanist; January 26, 2015 at 00:45. Reason: Typos
smanist is offline   Reply With Quote

Old   January 26, 2015, 18:05
Default
  #2
hlk
Senior Member
 
Heather Kline
Join Date: Jun 2013
Posts: 309
Rep Power: 13
hlk is on a distinguished road
Thank you for your question

For changing the flight conditions, please note that the solution will be sensitive to the quality of the mesh, and that a mesh that is well tuned for a particular Reynolds number and Mach number may not perform well at other conditions due to not having enough refinement in the boundary layer or near shocks. Similarly, when switching between models a different mesh may be needed - especially when switching between an inviscid (euler) and viscous model (rans).

If you have not done so already, I recommend making a new mesh for the wedge which has y+ <= 1 at the wall. (cfd-online has a calculator that can help with this at http://www.cfd-online.com/Tools/yplus.php).

Quote:
Originally Posted by smanist View Post
Hi guys,

I have just begun using SU2, which I hope I can use to simulate hypersonic flow with real gas effects. I assumed that is possible, because I noticed the existence of TNE2 module in SU2. I have tried the RAMC-II test case and ran a Mach 12 double-wedge airfoil case for Euler solution. They worked well.

However, when I try to get RANS solution of the double-wedge case, I get this error
Code:
------------------------------ Begin Solver -----------------------------

!!! Error: There is a NaN in the residual. Now exiting... !!!
In my case, I configured flow condition to be H=12km in atmosphere,
Code:
FREESTREAM_TEMPERATURE= 220.61
REYNOLDS_NUMBER= 8.07145E7
REYNOLDS_LENGTH= 1.0
The output of SU2 is correct, as it shows
Code:
Specific gas constant: 287.058 N.m/kg.K.
Free-stream pressure: 20646.1 Pa.
Free-stream temperature: 220.61 K.
Free-stream density: 0.326019 kg/m^3.
Free-stream velocity: (3573.08, 0) m/s. Magnitude: 3573.08 m/s.
Free-stream total energy per unit mass: 6.54177e+06 m^2/s^2.
Free-stream viscosity: 1.44323e-05 N.s/m^2.
For the rest of the configure file, the key settings are, (the whole file is just too long to be posted here)
Code:
PHYSICAL_PROBLEM= NAVIER_STOKES
KIND_TURB_MODEL= SA
VISCOSITY_MODEL= SUTHERLAND
MARKER_HEATFLUX= ( UPPER, 0.0, LOWER, 0.0 ) % Wall BC
MARKER_FAR= ( INLET, OUTLET ) % Farfield
CONV_NUM_METHOD_FLOW= ROE
SPATIAL_ORDER_FLOW= 2ND_ORDER
SLOPE_LIMITER_FLOW= VENKATAKRISHNAN
TIME_DISCRE_FLOW= EULER_IMPLICIT
CONV_NUM_METHOD_TURB= SCALAR_UPWIND
SPATIAL_ORDER_TURB= 2ND_ORDER
SLOPE_LIMITER_TURB= VENKATAKRISHNAN
TIME_DISCRE_TURB= EULER_IMPLICIT
I also tried Mach 2 (Re=1.34524E7), after several iterations, same issue happens. For Mach 3 (Re=2.01786E7), same thing, except that there is also a message,
Code:
There are 4 non-physical states in the upwind reconstruction.
I am still playing with the setting to see what happens. Any idea what might be wrong here? Any help will be appreciated.

Thank you in advance!
Danny
hlk is offline   Reply With Quote

Old   January 26, 2015, 21:03
Default
  #3
New Member
 
David Hwang
Join Date: Feb 2014
Posts: 5
Rep Power: 12
smanist is on a distinguished road
I see! Thanks for your advice. Let me refine my mesh.
smanist 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
buoyantSimpleFoam and watertank Tobi OpenFOAM Running, Solving & CFD 100 December 18, 2022 08:15
Cannot run the code properly: very large time step continuity error crst15 OpenFOAM Running, Solving & CFD 9 December 14, 2014 18:17
SixDoFRigidBodyMotion under OF2.3 ( self oscillating cylinder) Scabbard OpenFOAM Running, Solving & CFD 1 July 22, 2014 04:50
pisoFoam with k-epsilon turb blows up - Some questions Heroic OpenFOAM Running, Solving & CFD 26 December 17, 2012 03:34
Could anybody help me see this error and give help liugx212 OpenFOAM Running, Solving & CFD 3 January 4, 2006 18:07


All times are GMT -4. The time now is 08:50.