Development of multiphase solver for the modeling of turbidity currents (the case study of Dez Dam)

Abstract

Dams in semi-arid regions, like Iran's Dez dam, are losing their capacity by sedimentation. Settling sediments reduces clear water, and hydropower plants' efficiency. Reservoir sedimentation relies on turbidity currents (TC). TC head velocity, and sediment content both affect particle tracking, and the removal from reservoirs. To comprehend the TC properties of Dez dam reservoir, large-scale TC modeling is required. To represent large-scale TC, a novel solver is developed. This solver couples a modified OpenFOAM® interFoam solver with the particle concentration transport equation. Two experimental tests, and Dez dam field data were verified and calibrated. The novel solution modeled these instances utilizing a two-dimensional vertical model (width averaged) with RANS turbulence closure, despite the fact that the Dez dam reservoir has a considerable size for numerical modeling. The solver simulated four Dez Dam reservoir scenarios with different water levels. Consequently, when the inlet water depth rose four times, the TC head velocity, and distance traveled by TC doubled. TC in Dez dam is a supercritical flow with the interface instabilities based on its local Richardson number, and gradient Richardson number. Furthermore, Kelvin-Helmholtz instabilities and recirculation vortex combine clear water with TC to reduce the particle concentration.