Learning Forum

[Pablo Tagle]

Dear Ansys community,

I trust this message finds you well. I am currently working with Fluent and have a question concerning the treatment of adiabatic surfaces within the software. As a relative beginner in the field, I am still navigating the intricacies of CFD simulation and would greatly appreciate your expertise and insights.

In the theoretical context, an adiabatic surface implies a heat flow of precisely zero, suggesting either perfect insulation or an absence of temperature gradient. My specific query is whether the software treats this condition as exactly zero or internally assigns a minute non-zero value (commonly referred to as "eps").

I am keen to understand the numerical considerations involved in the treatment of adiabatic surfaces in Fluent. If there are any relevant documents or resources that delve into this topic, I would greatly appreciate it if you could point me in the right direction.

Thank you sincerely for your time and consideration. Your assistance in shedding light on this matter would be invaluable to my work.

Best regards,

[SRP]

Hi,

The handling of adiabatic surfaces in Fluent is often predicated on the assumption of zero heat transfer. However, obtaining zero heat transfer can be difficult numerically due to a variety of factors such as discretization errors, solver settings, and numerical approaches. To address instances when values approach zero, Fluent utilises a tiny numerical tolerance. This is done to avoid numerical instability and to ensure stable convergence. While this number is incredibly tiny and in most practical instances it is zero.

Hope this helps you.

Thank you.