translocation with hydrodynamics effects

I want to simulate polymer translocation throught a nanopore.I made a wall with a cylindrical pore in its center and i set this wall as a mambrane in middle of a box. I set the first bead of polymer (bead-spring chain) inside the pore. In order to take account into hydrodynamics effects on polymer translocation, i used fix srd command to make srd particles as a background solvent.Apparently srd paticles just do interact with the solute particles.So srd particles could not do interact with particles of wall and they passed from wall. But i want srd particles can do interact with wall’s particles by a repulsive potential in order to have an impermeable membrane.So i think i can use fix wall/srd command to solve this problem.
If it is possible for you ,please help me how i make a wall can do interact with both srd particles and polymer as the solute paticles simultaneously?
Thanks
Samira

Fix wall/srd is an idealized flat wall. If you want to build
a wall of particles, then simply make it dense enough that
there are no holes, and SRD particles will bounce off
the wall particles just as they would bounce off solute
particles.

Steve