How to handle different grid spacing in X,Y and Z in Palabos?

I try to simulate flow through a fractue with big fracture surface (5 x 2.5 cm) but very small aperture (10s of micron). The grid spacing for fracture surface in x and y direction are of 100 um with grid numbers 512 x 256, while spacing in z direction for aperture is 0.5 um with grid numbers of 200. How can I handle the different spacing in x,y and Z? If I decrease the spacing in x-y as in z, the grid number would be too huge, while if I increase the spacing in z to x-y, the resolution would be too low to see the aperture.

Thanks in advance.

Simple answer: you can’t. LBM relies on a regular grid.

best regards