Reply To: Getting velocity distributions.
Indeed, glad you were able to find this method on your own.
As for the other part of your question: The way that a given macroscopic quantity such as density or velocity is mapped into the mesoscopic population values depends on the specific local model of the specific cell. Generally speaking this is done by computing the equilibrium distribution that represents these specific macroscopic moments.
Further details of these basic LBM concepts are available in our user guide or for example in the LBM book by Krueger et al.