p. omidvar

Sediment transport in the aquatic environment is one of the complex two-phase problems in flow mechanics and sediment hydraulics. In this study, the interaction between water and sediment is explored using the SPH method and developed SPHysics2D in which the pressure values are calculated using the state equation. In this study, the non-Newtonian rheological model µ(I) is used for modeling the sediment phase where it is developed based on the properties of granular particles. Also, the effective pressure is used for the study of sediment behavior. The method used in this research is compared with the methods used by other researchers. The Owen equation is utilized to determine the effect of viscosity within the two-phase area. The developed method is evaluated by the dam break on a dynamic bed and then, the experimental model of submerged sediment column collapse is investigated in the aquatic environment. The results of the modeling demonstrate the capabilities of the developed code for the use in the flow and sediment hydraulics.

Investigating dense flows containing cohesive sediments (turbidity currents) in water environment has been a main interest for researchers in hydraulic and fluid mechanic science. This kind of flow streams at bed surface because of higher density than water and penetrate to overhead water, which causes turbidness.  In the following research, this kind of flow has been modeled using two-phase simulation with smoothed particle hydrodynamics Lagrangian method. A SPHysics2D code has been developed for modeling, in which pressure value is explicitly calculated using equation of state. Also, Herschel-Bulkley-Papanastasiou single relation non-Newtonian viscoplastic model has been used for modeling cohesive sediment phase. After that for investigating the amount of penetration of cohesive sediment mixture in limpid water, advection-diffusion equation was used for developing code. Finally, one and two phase results obtained from the present model were compared to experimental models. The study shows that the present developed model is able to model these flows desirably and could be utilized for studying concentration amount, dense flow penetration and their propagation in water environment.