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To analyze the flow in a rockfill porous media using the Gradually Varied Flows theory (one-dimensional flow analysis) and solving the Parkin equation (two-dimensional flow analysis), calculation of the output flow depth as the downstream boundary condition is of great importance. In most previous studies, the output flow depth has been considered equal to the critical depth. In the rockfill porous media, unlike free surface channels, the fluid weight is exerted to the aggregates in addition to the flow, and therefore, the output flow depth from the rockfill is always greater than the critical depth (flow leaves the rockfill with a specific energy greater than the critical energy), and is expressed as a coefficient (Γ) of the critical depth. In the present study, using dimensional analysis and particle swarm optimization (PSO) algorithm and experimental data in different conditions (a total of 178 experimental data for rounded, crashed, Glass artificial materials with rhomboid structure, Glass artificial materials with cubic structure, sandy natural materials), an equation was presented to calculate the mentioned coefficient as a function of the physical characteristics of the rockfill porous media as well as the flow that can be used for all experimental conditions with high accuracy. If the output flow depth is considered to be equal to the critical depth, the mean relative error (MRE) in terms of using the experimental data of the mentioned materials separately and for the data of all the mentioned materials together was equal to 84.40, 83.81, 60.62, 67.68, 74.82 and 69.96%, respectively. In the case of using the proposed equation in the present study, the corresponding values of 5.49, 4.72, 6.24, 4.41, 6.42 and 8.99% were calculated, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the numerical results of impulsive waves generated by landslides of solid block, granular materials and heavy block sinking. An impulse product parameter P is developed and a wide range of effective parameters are studied. The volume-of-fluid (VOF) and overset mesh methods have been used to study landslide-generated tsunamis. Also, a Lagrangian tracking approach coupled with the VOF to simulate the granular movement was developed. The effect of the water reservoir depth, the landslide height, the landslide density and the geometrical parameters on the wave height (elevation) has been investigated using the open-source OpenFOAM software. The results have been presented for dimensionless distances and the normalized geometry of the landslide in the ranges 5-7, and 1-2, respectively. These numbers have been normalized to the height of the landslide (a). According to the results of simulations, the tsunami formation process is divided into three stages, which were analyzed in detail by considering the interactions between the solid and the water reservoir. The Scott Russell wave has the highest impulse product parameter among the impulse wave mechanisms which is 58.6% of the total impulse production. In addition, the duration of the wave propagation has been computed based on the wave height. [ABSTRACT FROM AUTHOR]

Uniform flow will become unstable when the channel slope is very steep. When this happens, the free surface will form a series of roll waves. This paper, using the Fluent software and applying the volume of fluid model to simulate free surface flow and the k -- ε turbulence model, analyzes conditions for roll wave formation in free surface flow with the aim of predicting their occurrence in chutes. This study describes how the type of cross-section of the chutes influences the formation of roll waves. Hydraulic characteristics of the flow in the physical model of the flood control structure for Azad Dam spillway, which consists of a side spillway, chute, and flip, are three-dimensionally simulated. Numerical predictions were compared against the experimental data and results show that there is a good agreement between numerical and experimental results. Results indicate that an increase in side slope tends towards flow stability and the slower formation of rolling waves. Also, the rolling waves are expected to be generated for sections of the chute when the difference between the maximum dynamic pressure and the minimum dynamic pressure in those sections is above 9,000 Pa. [ABSTRACT FROM AUTHOR]