[heisenmech]

Hi all,

I'm trying to simulate a flow over flat plate for some validation purposes. What I would normally do is to create a rectangular box and treat the top surface as symmetry. However, the paper I'm looking at defines the top boundary condition as follows;

"The top boundary conditions are u=Uinf, v=VBlasius, w=0, and T=Tinf "

Does anyone know how to define (in Fluent) such conditions on top of a domain (which is not an inlet obviously), which is basically a plate?

Cheers,
heisenmech

[LuckyTran]

It's actually is obviously velocity inlet.

[heisenmech]

Thanks for the reply. I wasn't sure about that until I gave it a try with quick setup simulation. I'm still wondering though why I cant use (or why one would use velocity inlet) a simple symmetry BC on top since the results are pretty much the same. Any thoughts?

Cheers,

[LuckyTran]

In my experience, more people use a symmetry BC at the top (or slip walls) than anything else. Yeah I can't tell you why this one particular person think it's unusable. To each their own. The choice of which to use is by the user. But each has to verify that they have a proper boundary layer in their simulation after-the-fact.

The BC that you want is the natural boundary condition these are all just ways to mimic that behavior. There is also a freestream BC in Fluent which might even be better than symmetry/slip/velocity BC.

[heisenmech]

Originally Posted by LuckyTran

In my experience, more people use a symmetry BC at the top (or slip walls) than anything else. Yeah I can't tell you why this one particular person think it's unusable. To each their own. The choice of which to use is by the user. But each has to verify that they have a proper boundary layer in their simulation after-the-fact.

The BC that you want is the natural boundary condition these are all just ways to mimic that behavior. There is also a freestream BC in Fluent which might even be better than symmetry/slip/velocity BC.

Do you mean "pressure far field" BC by free stream BC?

[LuckyTran]

Yes, probably. It has been a few days since I opened Fluent. =)

[heisenmech]

Fair enough Thanks for your replies LuckTran! Cheers!