Question on Steady vs Unsteady RANS in Code_Saturne
Posted: Tue Sep 16, 2025 11:47 am
Dear Yvan,
I would like to clarify how steady and unsteady RANS are selected in Code_Saturne. Am I correct that choosing Constant or Adaptive time step corresponds to unsteady simulations, while Steady (local time step) corresponds to a steady simulation (But why does the Steady option still require input of adaptive time-step parameters, is it the “pseudo-time”)?
In my case, I used the Adaptive time step option for a wall-bounded square cylinder. The flow should be unsteady, but the results appear nearly steady: the time history shows almost no variation, and the snapshots do not reveal vortex shedding. Do you have any suggestions on how to address this? Is there a specific option I need to enable for URANS?
For reference, I am using Code_Saturne 8.0 with an ABL inlet profile and wall functions at the wall. My setup.xml file is attached.
Best regards,
Ximeng
I would like to clarify how steady and unsteady RANS are selected in Code_Saturne. Am I correct that choosing Constant or Adaptive time step corresponds to unsteady simulations, while Steady (local time step) corresponds to a steady simulation (But why does the Steady option still require input of adaptive time-step parameters, is it the “pseudo-time”)?
In my case, I used the Adaptive time step option for a wall-bounded square cylinder. The flow should be unsteady, but the results appear nearly steady: the time history shows almost no variation, and the snapshots do not reveal vortex shedding. Do you have any suggestions on how to address this? Is there a specific option I need to enable for URANS?
For reference, I am using Code_Saturne 8.0 with an ABL inlet profile and wall functions at the wall. My setup.xml file is attached.
Best regards,
Ximeng