Free surface boundary conditions

[Wolfmeister7]

Dear OpenLB community,

I have plans to use OpenLB for my simulation. The problem includes the following features:

1. 2D-flow
2. turbulent flow (up to Re=10000)
3. bottom wall is solid, so there is no-slip boundary conditions there
4. periodic b.c. on vertical walls
5. free but non-deformable upper wall

And I have two questions.

Question number one – do I need MRT-scheme for Re=10000 or it is not obligatory and BGK will suffice?

Question number two. There are no problems in performing b.c. 3-4, but what about free non-deformable upper wall? I do not know, how to apply them. Is it possible at all? Or should I use Shan-Chan scheme for this in order to simulate this particularly boundary condition?

Thank you very much in advance!

• This topic was modified 1 year ago by Wolfmeister7.
• This topic was modified 1 year ago by Wolfmeister7.
• This topic was modified 1 year ago by Wolfmeister7.

[mathias]

1/ I would use a Smagorisky model in combination with BGK. For the free flow, I would set a Pressure BC (=Direchlet Zero for Pressure, Neumann Zero for Velocity).

[Wolfmeister7]

Thank you very much for your reply. I will use Smag. model with BGK.

One more clarification. I do not know about Pressure BC in OpenLB package, can it handle the following case: v(u, w), u=dw/dy=0 on the upper boundary?
Or Pressure BC handles it somehow different?

[mathias]

That is what pressureBC is doing.

[Author]

Posts