Timestep size and resulted residuals in transient DO radiation model (no flow)

  • Last Post 25 May 2020
hsm86 posted this 25 May 2020


I am doing transient heating for static fluid (fluid in a container, no flow). I knew that the timestep size depends on the mesh and velocity scales but the velocity is zero in my model. Should I use a very small timestep size like 0.001 or even smaller or can I use higher values like 1 or even 10 s to deal with the duration of my work which is 25 min. I've tried 10 s (screenshot attached) and gave me the same results when I used 0.5 s.Thank you

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abenhadj posted this 25 May 2020

Ansys staff do not look into the attachments. You might use larger time step sizes whenever this is possible. I assume that is the case where only diffusive energy transport is used without any flow and density variations. Just ensure residuals are law, domain imbalances are low and monitored quantities are depicting steady state behavior at towards the end of a time step.

Best regards, Amine

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hsm86 posted this 25 May 2020

Much thanks for your reply! I am attaching the screenshot here, hope this works .. I am using the DO model for radiation 

hsm86 posted this 25 May 2020

Also, I'd like to make sure about something else please .. when no flow in the model, can I disselect the flow and turbulence equations from the equations listed in case of radiation with heat transfer using the DO model? ..