Inlet velocity profile

[tartopomm]

Hello

I am using openLB for my thesis but I am completely new to it and to C++ , so I’m struggling with a pretty simple problem. I hope you could help me out with this.

In the cylinder2D example, I would like to add a constant inlet velocity profile (possibly increasing with time) instead of a Poiseuille profile. What changes should I do in the cylinder2D.cpp file ?

I’ve read some topics with similar questions but I didn’t manage to implement it.

Thank you for your help!

[mathias]

Dear tartopomm,

you can use a const analytical functor. They are used in the some example to fix the outflow pressure. Please, also have a look in our documentation on functors. Last but not least, consider to come to our next spring school which will help you to get started!

Best
Mathias

[tartopomm]

Thank you for your answer, I managed to get what I wanted!
Then, I would have another question: I would like to have a slip condition on the top and on the bottom of my domain, so I added this line where the boundary conditions are defined (velocity and pressure):

sBoundaryCondition.addSlipBoundary( superGeometry, 2)

But is it enough or should I add something else? because when I ran the simulation, it didn’t change much.

thank you!

[mathias]

Before you set

sBoundaryCondition.addSlipBoundary( superGeometry, 2)

you need to set a “doNothing” dynamics there.

Best
Mathias

[tartopomm]

So I added that line just before setting the slip boundary:

sLattice.defineDynamics( superGeometry, 2, instances::getNoDynamics<T, DESCRIPTOR>() )

but again, it didn’t change anything, did I miss something?

Thank you for your time!

[mathias]

Please,explain exactly what iyou think is going wrong. What version of OpenLB are you using? Is it the latest. We have tested the method serveral times.

Best
Mathias

[tartopomm]

I meant there was still a no-slip boundary condition on the top and on the bottom of the domain. I was using openlb 1.1.

i downloaded openlb 1.2 yesterday and indeed it worked perfectly well with your comments. thank you!

But how come it went wrong with openlb1.1 ?

[Author]

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