Help with a mfix-pic theory-doc

hello everyone, I am learning the mfix-pic, anyone who can give me a Help-document about the mfix-pic theory?

thanks !

Please start with The MFiX Particle-in-Cell Method (MFiX-PIC) Theory Guide - doe.netl-2020.2115_particle-in-cell-method-theory-guide_2020.05.22.pdf - EDX