SimScale CAE Forum

Incompatible Time Differentiation Scheme for Steady State


Hello. I am trying to do a steady state compressible simulation. Whenever I select steady state as my default time differentiation scheme, I get an error that says

"The time differentiation scheme is incompatible with this simulation setup. Please use a different scheme."

despite the fact that I have looked at other’s simulations with the same settings as me, who have done steady state as their time differentiation scheme. When I change the differentiation scheme to something like Euler or Backward, the simulation quickly comes to the error message

"The job execution was aborted, possibly due to a numerical instability. Review the log to identify reasons: nonphysically large field values, extremely small time step size, etc. Modifying numerical settings and time step size could resolve the issue."

which seems to me like it could be because I’m not using a steady state time differentiation scheme. Either way, I should be able to use the steady state scheme for a steady state simulation. I’m sure there is some small thing I am doing wrong, so please point it out.

Here is a link to my project.


Incompatible Time Differentiation Scheme for Steady State

Hi @aattenasio!

@PowerUsers_CFD, @Anware and me will shortly have a look at your project and see what might be wrong in your setup or even the mesh. Getting back to you asap!

All the best!



Thanks Jousef! Much appreciated.


Hi @aattenasio,

Try setting your “Write Control” under “Simulation Control” to “Adjustable Run Time”. You can keep the value of 500 the same. See if that can get your simulation past the failure point at least.

Do let me know how it goes!



Additional note @aattenasio!

I am currently running another (better) mesh with boundary layers as well as refined zones for the front edge as well as the trailing edge and an overall increased size for the bounding box domain. Posting the link to it as soon as I am finished :+1:

Edit: Invited you to the project. Mesh is called “Test”.




@Get_Barried - Tried changing to adjustable runtime, still got the error of incompatible time differentiation scheme.

@jousefm - I see the test mesh you made. Have you run a simulation on it yet? Also, would the invite come as an email? Not sure I see it anywhere on my profile.

Thank you both for your help! I appreciate it. I look forward to understanding why this doesn’t work, or at least having it fixed.


Hi @aattenasio!

You should get an invite via email! Have not run a simulation yet :slight_smile: The setup itself should be straightforward. Darren (@1318980) has some pretty nice simulations of airfoils which you can use as a template.

Please ask us if you need anything! All the best!



Sorry this may seem as if I am spamming this question.

Hello there, again I found a lot of questions regarding this topic but not a lot of them gave an answer towards the question, does anyone know how to fix this? I am currently working on a compressible steady state project on rocket nozzles, I’m trying to view the convergence and divergence airflow through the nozzle. Is there anyone that knows how to fix this, and does anyone have any suggestions to how I should approach making something like this?

If you’re curious on my project, you can view it here


@CFD-SQUAD, want to jump in here and help our user? :slight_smile: