محمد واقفی

In this research, flow was studied on convex and divergent staircase overflows and simple stepper overflow with finite volume numerical method using Flow-3d software. By comparing the results of the numerical model with the experimental results of Hunt et al. (2008, 2012), it was concluded that a numerical model can well simulate the flow on a convergent and divergent stepper overflow. Initially, numerical modeling of suitable boundary conditions, meshing with the desired dimensions and a suitable model of turbulence for describing the hydraulic flow on staggered and divergent wall stacks were obtained. Two models of disturbance of the two equations K-? and RNG K-?, and a model of turbulence of large vortices LES, were used. By comparing the experimental data with the numerical modeling results, the LES model has better correspondence with experimental data than other disturbance models. In the following, the effects of convergence and divergence of the stepwise overflow wall on energy depletion, flow velocity and cavitation risk were investigated. In this study, it was concluded that with increasing divergence angle, energy depreciation increases and downstream flow rate decreases. Also, in a convergent stepper overflow, with increasing angle of convergence, energy depreciation decreases and the flow velocity decreases. So that in a discharge of 1200 cubic meters per second, energy dissipation in a divergence overflow of 15 degrees, 20.43 percent, is greater than the convergence overflow at a 15-degree angle. Also, the downstream velocity in a simple step overflow state is 18.7 percent higher than the flow velocity in a stepped overflow with a diverging wall at 52 degrees, while the rate of increase in the flow velocity in a convergent overflow with an angle of 52 degrees over the overflow Simple steps are 27.7%. In the next study, the effect of stairs and gradient elevation elevation divergence was investigated. By studying the models, it was concluded that with i