Modify Boundary Conditions

[llestev]

Hello, everyone

I’m using OpenLB to compare some results to an LBM code I developed also in C++ for a project in university. It’s been a few weeks since I’m having problems to define different boundary conditions. I’m working based in the example cylinder2d. So far, I was able do modify the cylinder to a square (Cuboid2D), which is the obstacle I’m studying and change the domain size. I need to modify the upper and bottom boundary conditions to symmetry (or periodic, so that the domain size does not influence significantly the results), instead of the no-slip wall that is already setted. Also, I’d like to impose a uniform inlet velocity instead of a Poiseuille flow profile. I’ve already tried to figure it out through the openLB user guide, but I’m struggling to make these changes correctly. Can anyone help me on how I could implement these modifications?

I can share the source code if necessary, but as I mentioned before, I’m working based on the ‘cylinder2d’ example.

Thanks in advance,

Lucas Estevam

[llestev]

Hello, again

Can anyone tell me if it is possible to modify these conditions as I mentioned and if so, if there is some sort of material I could look up to?

[mathias]

Hi Lucas,

To get started, please, have a look at the other examples and also use the Doxygen documentation. Next spring, we also have a new spring school with a OpenLB software lab.

You may use sysmmetry conditions (=slip) or a perodic set-up. For the latter, there is e.g. the TGV example you can have a look how it is realised. A uniform inlet velecity is easy to set. You can use the “Const” functor, it is used in many example. In the user guide there is a section on the functor concept.

Best
Mathias

[llestev]

Thank you very much Mathias, I hadn’t used the Doxygen documentation yet and it helped me a lot, I managed to modify the parameters I mentioned before! Thanks again for the help.

All the best,
Lucas

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