geometry input

I am writing a matlab programm which can read staircase meshes. My aim is to simulate single-phase flows in micro channels with bounce-back boundaries.
I have problems transforming my discrete lattice data into physical units.

My first guess was to choose N = 1, but still I am getting a Segmentation fault.

Is there a systematic way to calculate the physical units if you have the lattice given?

Are there limitations on the lines of code you put in a case file?

@OpenLB crew: how far are your efforts for geometry input? I think it should give your promising project a big boost