I’ve developed a Lattice Boltzmann code utilizing the D3Q19 model to tackle fluid dynamics within complex geometries. For the inlet boundary condition, I’ve implemented the ZouHe method as outlined in the publication https://iopscience.iop.org/article/10.1088/1742-5468/2010/01/P01018. I’ve enforced a fully bounce-back condition for the walls and maintained a constant pressure at the outlet. However, I’ve encountered two issues with obtaining the desired results. Firstly, the ZouHe method isn’t setting the velocity as anticipated. Secondly, while I expect velocity components at the wall to be precisely zero, they instead exhibit small values. On wall also the density value is around 1.03 instead of being exactly 1 and this is suggesting there should be something wrong with the distribution function.
I’ll share a portion of my code and welcome any insights to resolve these issues. I can’t generate a reproduceable code but I can share any function if required.

I’ve developed a Lattice Boltzmann code utilizing the D3Q19 model to tackle fluid dynamics within complex geometries. For the inlet boundary condition, I’ve implemented the ZouHe method as outlined in the publication https://iopscience.iop.org/article/10.1088/1742-5468/2010/01/P01018. I’ve enforced a fully bounce-back condition for the walls and maintained a constant pressure at the outlet. However, I’ve encountered two issues with obtaining the desired results. Firstly, the ZouHe method isn’t setting the velocity as anticipated. Secondly, while I expect velocity components at the wall to be precisely zero, they instead exhibit small values. On wall also the density value is around 1.03 instead of being exactly 1 and this is suggesting there should be something wrong with the distribution function.
I’ll share a portion of my code and welcome any insights to resolve these issues. I can’t generate a reproduceable code but I can share any function if required.