Poiseuille 2D Center Velocity Error (Forced,bounceBack)

[achodankar]

Hello Developers,
I have a question regarding the pressure-driven parabolic Poiseuille flow. The top and bottom walls are subjected to a zero-velocity bounce-back condition while the inlet and outlet boundaries enforce a pressure-driven fully-developed flow condition using the generalised periodic
boundary condition method. The walls to be located at grid solid nodes leads to strongly deviating results, while walls located midway between grid nodes makes the LB solution coincide with analytical parabolic profile. Increasing the resolution of the model does reduce the error significantly. How should I set the walls midway between grid nodes in OpenLB? Is it by default that the wall nodes are located at the grid solid nodes?

Poiseuille 2D simulation run
Simulation parameters: forced, bounceBack

Thank you.

Yours sincerely,

Abhijeet

[mathias]

Standard bounce back in general work like this with the wall assumed to be located 1/2 off the nodes. In the mentioned example we have show how to realize it. Best Mathias

[achodankar]

Hello Mathias,
How should I get the numerical solution equal to the analytical solution for this case?

Thank you.

Yours sincerely,

Abhijeet

[mathias]

LBM is a second order scheme, i.e. the numerical solution will approach the analytical one up to an numerical error. Best Mathias

[achodankar]

Hello Mathias,
Thank you for the prompt response. I understand it now.

Thank you.

Yours sincerely,

Abhijeet

[Author]

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