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 Strömgren 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 \hskip { 2.0 pt } 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 1.5 t _ { \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 \hskip { 2.0 pt } 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 .