Suspended load movement is an important form of river sediment transport

and its existence in the flow poses a significant impact on flow turbulences. The movement is complicated

and no agreement has been reached on the mechanism of water-sediment interaction. This paper presents an application of the OpenFOAM two-phase flow model and its simulations of equilibrium sediment transport under different flow conditions

focusing on how the size

density and concentration of suspended sediment particles impact turbulent flow characteristics

and on the mechanism of flow turbulences modulated by drag force

density gradient

and particle collision. The results show that 1) with an increasing suspended particle size

the velocity of both the water flow and particles decreases overall

and the velocity gradient near the riverbed increases significantly; In the near-wall layer

sediment concentration gradient increase

turbulence intensity decreases first and then increases

and its peak values increase. 2) An increase in suspended particle density leads to an increase in the average turbulent flow velocity. The smaller the suspended particle density is

the more uniform the vertical concentration profile

and vice versa. 3) An sediment concentration increase reduces the average turbulent flow velocity and turbulence intensity

and the higher the concentration

the more obvious its suppressing effect. 4) An increase in drag force raises turbulent flow rate and suppresses turbulence intensity and sediment suspension. Suspended sediment density gradient has a suppressing effect on both bottom layer velocity and top layer turbulence intensity. Particle collision reduces average velocity and significantly enhances turbulence

thus promoting sediment suspension.