  We perform three-dimensional radiation hydrodynamic simulations of uniform
dusty gas clouds irradiated by an active galactic nucleus (AGN) to investigate
the dependence of evolution of clouds on the ionization parameter $\mathcal{U}$
and the Str{\"o}mgren number $\mathcal{N}_{S}$. We find that the evolution can
be classified into two cases depending on $\mathcal{U}$. In low $\mathcal{U}$
cases ($\mathcal{U}\approx 10^{-2}$), the evolution is mainly driven by
photo-evaporation. A approximately spherically-symmetric evaporation flow with
velocity of $100\operatorname{-}150\;\mathrm{km\;s^{-1}}$ is launched from the
irradiated face. The cloud is compressed by a D-type shock with losing its mass
due to photo-evaporation and is finally turned into a dense filament by
$t\lesssim 1.5t_{\mathrm{sc}}$. In high $\mathcal{U}$ cases
($\mathcal{U}\approx 5\times 10^{-2}$), radiation pressure suppresses
photo-evaporation from the central part of the irradiated face, reducing
photo-evaporation rate. A evaporation flow from the outskirts of the irradiated
face is turned into a high velocity ($\lesssim 500\;\mathrm{km\;s^{-1}}$) gas
wind because of radiation pressure on dust. The cloud is swept by a radiation
pressure-driven shock and becomes a dense gas disk by $t\approx
t_{\mathrm{sweep}}$. Star formation is expected in these dense regions for both
cases of $\mathcal{U}$. We discuss the influences of the AGN radiation on the
clumpy torus. A simple estimate suggests that the clumps are destroyed in
timescales shorter than their orbital periods. For the clumpy structure to be
maintained over long period, the incident radiation field needs to be
sufficiently weaken for most of the clumps, or, some mechanism that creates the
clumps continuously is needed.
