  Using cosmological $N$-body simulation which coevolves cold dark matter (CDM)
and neutrino particles, we discover the local effect of massive neutrinos on
the spatial distribution of CDM halos, reflected on properties of the Delaunay
Triangulation (DT) voids. Smaller voids are generally in regions with higher
neutrino abundance and so their surrounding halos are impacted by a stronger
neutrino free streaming. This makes the voids larger (surrounding halos being
washed outward the void center). On the contrary, larger voids are generally in
regions with lower neutrino abundance and so their surrounding halos are less
impacted by neutrino free streaming, making the voids smaller (surrounding
halos being squeezed toward the void center). This characteristic change of the
spatial distribution of the halos suppresses the 2-point correlation function
of halos on scales $\sim$ 1 Mpc$/h$ and significantly skews the number function
of the DT voids, which serve as measurable neutrino effects in current or
future galaxy surveys.
