Voids and Superstructures: correlations and induced large-scale velocity
  flows
  The expanding complex pattern of filaments, walls and voids build the
evolving cosmic web with material flowing from underdense onto high density
regions. Here we explore the dynamical behaviour of voids and galaxies in void
shells relative to neighboring overdense superstructures, using the Millenium
Simulation and the main galaxy catalogue in Sloan Digital Sky Survey data. We
define a correlation measure to estimate the tendency of voids to be located at
a given distance from a superstructure. We find voids-in-clouds (S-types)
preferentially located closer to superstructures than voids-in-voids (R-types)
although we obtain that voids within $\sim40~\mathrm{Mpc}\,\mathrm{h}^{-1}$ of
superstructures are infalling in a similar fashion independently of void type.
Galaxies residing in void shells show infall towards the closest
superstructure, along with the void global motion, with a differential velocity
component depending on their relative position in the shell with respect to the
direction to the superstructure. This effect is produced by void expansion and
therefore is stronger for R-types. We also find that galaxies in void shells
facing the superstrucure flow towards the overdensities faster than galaxies
elsewere at the same relative distance to the superstructure.
  The results obtained for the simulation are also reproduced for the SDSS data
with a linearized velocity field implementation.
