LBM, 2D Poiseuille flow

niles_m · January 4, 2014, 07:12

Hi

I am trying to implement the 2D Poiseuille flow with the Lattice Boltzmann method, and I am using "on-grid bounce back" boundary conditions.

I have implemented it, but my velocity-profile is strange. There is a finite velocity at the boundary, but I was under the impression that the whole point of the bounce-back BC was to ensure no-slip. My velocity profile looks like this.

Does this behavior at the boundary imply an error in my implementation?

I'd be happy to post my code, if anyone is interested in taking a look.

Thanks in advance,
Niles.

akOOma · January 4, 2014, 08:46

It's been quite a while since I implemented LBM for channel flow.
But it should be correct, that you get a finite velocity at the walls.
The magnitude of this velocity depends on your lattice size. If you decrease the mesh size, the velocity at the walls should tend to zero.

January 4, 2014, 07:12	LBM, 2D Poiseuille flow	#1
niles_m New Member Niles Join Date: Jan 2014 Posts: 1 Rep Power: 0	Hi I am trying to implement the 2D Poiseuille flow with the Lattice Boltzmann method, and I am using "on-grid bounce back" boundary conditions. I have implemented it, but my velocity-profile is strange. There is a finite velocity at the boundary, but I was under the impression that the whole point of the bounce-back BC was to ensure no-slip. My velocity profile looks like this. Does this behavior at the boundary imply an error in my implementation? I'd be happy to post my code, if anyone is interested in taking a look. Thanks in advance, Niles.

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January 4, 2014, 08:46		#2
akOOma New Member Michael Woopen Join Date: Nov 2010 Location: Aachen, Germany Posts: 12 Rep Power: 15	It's been quite a while since I implemented LBM for channel flow. But it should be correct, that you get a finite velocity at the walls. The magnitude of this velocity depends on your lattice size. If you decrease the mesh size, the velocity at the walls should tend to zero.