polymer motion

What command could i use instead of fix langevin to simulate motion of polymer along with SRD particles?
Should i use just velocity command to make motion in monomers of polymer when i use fix srd command to take account hydrodynamics effects in polymer dynamics?


I don't understand what you want to do, or why you
think fix srd is a good way to do it. If you put a polymer
in a background SRD fluid, then the polymer will
move, similar to what it would do with fix langevin
an no explicit solvent.