  We perform a statistical study on the distribution and dynamics of voids in
the 2dFGRS. Our statistics are tested and calibrated using mock 2dFGRS
catalogues. We analyse the dynamics around voids in mock and real 2dFGRS
surveys. The void-galaxy cross-correlation redshift-space distortions show
evidence of the continuing growth of voids, confirming another prediction of
the hierarchical clustering scenario. A non-linear outflow model can be used to
provide quantitative estimates of the outflow velocities around 2dFGRS voids.
These results are consistent with maximum outflows of 110km/s, 210km/s and
270km/s for voids of <r_void>=7.5, 12.5 and 17.5h^-1Mpc, assuming a galaxy bias
of b=1. As an application for future surveys, our study of the mock catalogues
shows that direct measurements of the expansion of voids can be obtained using
peculiar velocity data. We find that it would also be possible to detect
differences in the velocity dispersion of galaxies in the directions parallel
and perpendicular to the void walls.
