non uniform

I use the LBM for studying flow around obstacle
I wrote a code in fortran with a regular mesh and I used f(k,i,j) where k for the 9-bit lattce node and i and j for the space node, then I computed the pressure p(i,j) and the macroscopic velocity u(i,j)and there is not a problem in the results. Then i want to use a non uniform mesh so i defined an irregular mesh with x(i)=x(i-1)+dx and y(j)=y(j-1)+dy where dx and dy varies .
my question is if I have to compute the f(k,i,j) - like regular mesh- then doing interpolation?
or introduce x(i) and y(j) in all variables (f(k,x(i),y(j)); u(x(i),y(j));p(x(i),y(j)))?
thank you for help