printfluid and output

Hi I’m using

printfluid in lattice boltzmann in order to find the velocity of each grid point. my simulation box is :

-20.0000 20 xlo xhi
-15.0000 15 ylo yhi
-15.0000 15 zlo zhi
amd I’m using this command for lattice boltzmann :
fix flu all lb/fluid 5 1 3.0 0.864 setGamma 20 dx 5 noise 1 812823423 calcforce 1000 poly printfluid 1000
the problem is that I do not understand in what order the printfluid prints the result, I mean how can I find which line of the output corresponds to a specific lattice grid point. My output for a step is this :

density u_x u_y u_z