Force term in simulation of multiphase with LBM

I am researching the multiphase flows using the lattice Boltzmann method. When considering the force terms, I modified the standard LB equation by adding the term of δf according the article of GUO. But what I want to ask is how should I modify the function of g ( g is the distribution function of order parameter ) in the model of Shan-Chen. Could anyone help me ? Thanks for your any reply…

You might want to check out the following article:
Forcing term in single-phase and Shan-Chen-type multiphase lattice Boltzmann models