The stilling basin has been accepted to be the most powerful hydraulic structure for the dissipation of the flow energy. The size and geometry of the stilling basin affect the formation of flow patterns, which can be influential for hydraulic performance of the whole system. The Nazloo Dam in Iran was selected as the study area. The USBR II stilling basin was conducted for four convergence angles (5 • , 7.5 • , 10 • , and 12.5 • ). The convergence walls cause the jump to stabilize inside the basin and cause the energy loss to increase in the stilling basin. To simulate the hydraulic jump in the convergence stilling basin conditions in this region, a free surface computational fluid dynamics (CFD) numerical model has been applied. The commercially known software, FLOW-3D , was applied to numerically solve the Navier-Stokes equations for solution domains, namely the shout, the stilling basin and the downstream of dam, and to estimate the turbulence flow, the standard k-ε and RNG models was used. These models are based on the volume-of-fluid method, and they are capable of simulating the hydraulic jump. The calculated results such as the pressure, the velocities, the flow rate, the surface height air entranced, the kinetics energy, the kinetics energy dissipated, and the Froude number were compared with the scale model data where available. This allowed a comparison for the use of CFD as a cost-effective alternative to physical models. The physical model and CFD model results showed good correlations.

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Hydraulic jump is one of the rapidly varied flows that different elements can be employed to control it in stilling basins. The purpose of this study is optimal design of obstacles at USBR II stilling basin of Nazloochay dam model. For this purpose, the obstacles at the end chute with thicknesses and heights of 0.5, 1, 1.5 and 2 m and 2, 3 and 4 steps at the end USBR II stilling basin have been considered. Then for the most optimal state, the pressure, water surface profile, turbulent kinetic energy, and turbulent kinetic energy dissipation investigated for discharging 830 m 3 /s by using K-ε and RNG turbulence model and VOF method. According to changes in water height, obstacles selected with heights of 1 and 1.5 equal of standard state at the end chute and 3 steps at the end stilling basin. The comparison of numerical and experimental values of water surface and pressure profiles showed that numerical model has good agreement with experimental results. Also, hydraulic jump on adverse steps at the end stilling basin increase energy dissipation and stability of hydraulic jump. In addition, numerical model can be used to model stilling basins and measuring non-measurable parameters in laboratory.

In this study, non-linear behavior of steel frames with dual lateral loader system with convergent crossing and chevron bracing equipped with linear and non-linear liquid viscose dampers in 8 and 12 story models as 2D under the record of near and far field to fault earthquakes are studied, evaluated and compared. For doing time history non-linear analyses, non-linear analysis software of Perform-3D has been used. This research absolutely confirms that viscose dampers reduces structure's responses under the effect of near and far field to fault records in a way that using non-linear viscose dampers in dual steel frames, the rate of created reduction is under the effect of near field records and more.