CFD Online Logo CFD Online URL
Home > Forums > CFX

Multiphase reaction Solver Error

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

LinkBack Thread Tools Display Modes
Old   April 4, 2006, 06:59
Default Multiphase reaction Solver Error
Posts: n/a
My problem consists of a "Reacting Mixture(with 4 gases)",a solid (MultiPhase-Eulerian) Out of these, the solid and a gas are formed after the reaction.

I am finding it really difficult trying to obtain the results.

I get this error and the run stops.

For all the 4 gases and the solid, I have entered the Cp values as a function(User function) of temp. These Cp values, ref entropy, ref enthalpy have been taken from the NASA thermobuild.

As you can see in the above link, I have tried increasing the Newton Iteration Limit to 200, but of no avail. I have also increased the pressure limits for each gas and the solid.

How do I debug this?

  Reply With Quote

Old   April 4, 2006, 09:14
Default Re: Multiphase reaction Solver Error
Posts: n/a
Dear Hagupta,

Have you tried the same simulation with constant properties already provided?

Either your properties are not thermodynamically consistent among themselves? Your time tstep may be too large...

You may need to talk to CFX help desk..

Good luck, Opaque..
  Reply With Quote

Old   April 4, 2006, 10:11
Default Re: Multiphase reaction Solver Error
Posts: n/a
Thank you, Opaque

Only 2 of the materials that I use are predefined in CFX. So, I have not yet tried the simulation with constant properties already provided.

1) So, should I try the simulation with 3 user materials and 2 CFX materials OR try a similar reaction (1 solid and 4 gases) taking all 5 CFX materials?

2) The auto timestep value was around 2.5e-5. The least timestep I have tried is 1e-5. Should I try reducing this to 1e-7 or still lower?

If the above 2 steps do not lead me to the solution, I think I will talk to the CFX help desk.

  Reply With Quote

Old   April 8, 2006, 09:43
Default Re: Multiphase reaction Solver Error
Posts: n/a
I tried with reduced timesteps the following 2 runs:

1) Single Phase with const prop. After several iterations(much more than what it used to be earlier) the solver crashed with "Floating point exception" error. Just before this error, I got "The Mach number exceeds....." error.

2) Multiphase with the value of "Minimum volume fraction for Mixture/Solid fluid pair set to the minimum possible(1e-15). This too crashed with "floating point exception-division by zero" error.

I was searching for the possible causes for this error and found a coarse mesh as one of the possible causes. Both of the above 2 setups had the same very coarse mesh. I have been using the coarse mesh to save time since I run it on a single processor.

So, how do I proceed further? Interpolate the results from the last saved .bak file onto a finer mesh and continue?

Regards, hagupta
  Reply With Quote


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
Error in CFX Solver Leuchte CFX 5 November 6, 2010 07:12
Accessing phi from a fvPatchField at same patch johndeas OpenFOAM 1 September 13, 2010 20:23
groovyBC sega OpenFOAM Running, Solving & CFD 12 February 17, 2010 10:30
Compiling problems with hello worldC fw407 OpenFOAM Installation 21 January 6, 2008 18:38
error while compiling the USER Sub routine CFD user CFX 3 November 25, 2002 16:16

All times are GMT -4. The time now is 22:05.