A near-boundary modification for the link bounce-back boundary condition in the lattice Boltzmann method

The bounce-back boundary condition in the lattice Boltzmann method distorts curved or inclined boundaries by forcing them to conform to a rectangular grid. This paper proposes a modification that reduces the effect of this discretization on the fluid flow. The modification takes the form of the addition of a type of node that is neither solid nor fluid, called the "sticky node". Sticky nodes are used in all cells that contain both fluid and solid. They are treated like fluid nodes with modified viscosity, body force, and velocity calculation. The method is applied to the LBGK model on a D2Q9 grid, and the accuracy of the method is evaluated using several test cases. Decreased discretization artifacts and decreased sensitivity to grid alignment are demonstrated, compared to the standard link bounce-back boundary condition. The method is computationally efficient, local, and demonstrates good numerical stability.