wet granular minxing

Hi every one....!
i am trying to simulate a mixer that contain glass beads with impeller in the middle.I am a new user of LIGGGHTS. i want to simulate wet mixing with 4 % moisture content,my problem is that i don't know how to add moisture content in the attached input file.Attached file is actually for dry mixing. My system contain 27000 glass beads with 3 mm dia.

Thanks every one.