[manar]

Hello Guys
I have a question regarding the steady analysis :
*How to justify the fluid velocity if it is a steady state problem , I know if the fluid is moving that mean it does not come to steady-state completely n is there any criteria for that ?
*about convergence : are the default residuals minimum ? what if I got 2.5e-2 for continuity residual for example ?????/?

[Antanas]

Originally Posted by manar

I know if the fluid is moving that mean it does not come to steady-state completely

You're wrong. Based on conditions flow can come to steady-state regime which means that its parameters don't change with time in every spatial point of flow region, that is flow pattern is steady (frozen) in time.

[manar]

thanks Antanas
sorry I am not familiar with Fluent that much , what I got from you is that Fluent consider steady state when the fluid parameters come into zero in the edges , ie:Outlets and walls , Is that correct ?

[LuckyTran]

It might be clearer if you call it steady-flow. The rate of flow attains a steady value (velocity is time-independent).

Velocity going to zero at walls is a boundary condition.

Velocity =0 at an outlet is paradoxical, either there is no flow or it is not an outlet.

[Antanas]

Originally Posted by manar

thanks Antanas
sorry I am not familiar with Fluent that much , what I got from you is that Fluent consider steady state when the fluid parameters come into zero in the edges , ie:Outlets and walls , Is that correct ?

Not at all. It's not about Fluent, it's about physics. Steady flow regime means that in the process of fluid flow its parameters (velocity, pressure, density etc.) at every point in the flow don't change with time. Understand? In steady flow parameters may vary only spatially.

[manar]

very clear Antanas and Lucky Tran