  We numerically study the effects of constrained interacting dark energy
(CIDER) on the bound-zone velocity profiles around massive dark matter halos.
Analyzing the CIDER simulations performed by Baldi (2023) for three different
cases of dark sector coupling ($\beta=0.03$, $0.05$ and $0.08$) as well as for
the standard $\Lambda$CDM cosmology ($\beta=0$), we determine the mean peculiar
velocity profiles in the bound zones around the friends-of-friends halos with
masses larger than $M_{\rm cut}=3\times 10^{13}\,h^{-1}M_{\odot}$ at three
redshifts, $z=0$, $0.5$ and $1$. It is found that the universal power-law
formula proposed by Falco et al. (2024) originally for the $\Lambda$CDM case
still describes well the bound-zone velocity profiles, $V(r)$, even in the
CIDER models. The slope of $V(r)$, turns out to be significantly affected by
the CIDER, progressively decreasing as $\beta$ increases. Meanwhile, the
amplitude of $V(r)$ exhibits little dependence on $\beta$, which is ascribed to
the identical Hubble parameters shared by the $\Lambda$CDM and CIDER models in
the entire redshift range. Our results imply that the bound-zone velocity slope
can break a degeneracy even between the $\Lambda$CDM and CIDER models with
$\beta\le 0.03$, which the standard cosmological diagnostics fail to
distinguish. We devise a simple analytic formula for the bound-zone slope as a
function of $\beta$, and prove its validity at all of the three redshifts. It
is concluded that the slope of the mean bound-zone peculiar velocity profile
should be in principle a powerful probe of dark sector interaction.
