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Accurate investigation of physical phenomena is one of the important challenges in engineering fields. The present study is about a wet tank which entrance of water is investigated in three cases. When the water wave moves into a tank, complex flow regimes are created. This complexity is mainly associated with different flow mechanisms during the entrance of water and propagation of waves at the bottom bed that should be modelled by means of Navier-Stokes equations with free-surface capability and in 3D phase. Due to complexity and time consuming of Navier-Stokes equations modelling, Shallow water equations are used with the assumption of hydrostatic pressure. First case is about efflux over a wet bed. Second, water influx from the middle top is investigated and then influx from top edges is modelled. A dimensionless number is introduced for each case based on water velocity, gap length and drop height which shows acceptable domain for appropriate compatibility between results. Finally, results of numerical modelling are compared with Navier-Stokes solutions which are obtained from STAR-CD software. Results show admissible compatibility with each other based on observations and inspections.

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Modelling of flood waves within surface and subsurface network is quite complicated. This complexity is mainly with respect to different flow regimes propagation into the sewer network which interacts with each other at connections between underground networks. The main purpose of the present paper is modelling and hydrodynamic prediction of these types of bore interactions using the shallow water equations. The shallow water equations are then solved using a second-order accurate HLLC Riemann which is able to model the wave propagation over wet and dry states based upon a combination of particular Riemann wave speeds. Friction terms are treated in a separate way within the associated source terms. First, the numerical solver is employed to model the shock and rarefaction waves over the wet and dry states and the achieved numerical results are compared with the exact solution. Then, the effect of friction terms for the one-dimensional dam failure propagation over wet and dry bed is considered and the computed results are compared with the STAR-CD which is a Navier-Stokes solver. Finally, two-dimensional flood wave propagation is modelled within a rectangular sewage section and the obtained results are validated with the three-dimensional STAR-CD results. The numerical results demonstrate that the defined numerical solver in both one and two-dimensional provides very good agreement with the exact solution and Navier-Stokes solver.

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In this paper a Godunov-type finite volume method is used for the solution of bedload sediment transport dynamics. The utilised equations for this modelling comprise the shallow water equations used for the hydrodynamic phase and also the Exner equation applied for the morphodynamic variations. These set of equations are then solved using a weakly-coupled scheme based on an augmented Riemann solver. In this approach the morphodynamic equation is first solved and the updated bedload changes with the same Riemann structure are used as a source term within the shallow water equations. The proposed numerical model is first used for the simulation of the parabolic sediment layer and the obtained numerical results are validated with the exact solution. Then, a bedload hump propagation with an initial subcritical condition which is able to create both mild and strong sediment and free-surface interactions is considered and the computed results are compared with the reference solution. These numerical results indicate that the defined weakly coupled method developed based on an augmented Riemann technique is able to be used for modelling bedload sediment transport for all flow regimes and exhibits a very good agreement with analytical or reference solutions for the given test cases.

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Various numerical methods have been developed for solving morphodynamic systems, among which the finite-volume method has been widely employed in recent years. This paper presents an efficient finite volume technique for simulation of bedload sediment transport near dry interfaces. The equations governing sediment transport in channels and rivers comprise the shallow water equations and Exner equation. By considering a novel velocity for Riemann waves, shallow water and Exner equations are solved using a weakly-coupled scheme based on an augmented Riemann solver. In this approach the morphodynamic equation is first solved and the updated bedload changes with the same Riemann structure are used as a source term within the shallow water equations. Augmented Riemann solver is based on a decomposition of an augmented vector—the depth, momentum as well as momentum flux and bottom surface. The proposed numerical model is first used for the simulation dam break flow over a mobile bed. Then, dam failure due to over-topping flow is considered and the computed results are compared with the experimental data.These numerical results indicate that the defined weakly coupled method developed based on an augmented Riemann technique is able to be used for modelling bedload sediment transport near dry interfaces with highly accurate and exhibits a very good agreement with the experimental data for test cases.

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In this paper a modified Godunov-type wave propagation algorithm is utilised for the modelling of falling water wave over a dry bed. The defined numerical model is well-balanced and is capable to treat the influx/efflux source terms and also the friction term within the flux-differencing of the finite volume neighbouring cells. Additionally, the method employs a rather simple HLLE wave speed for the propagation over dry-state. First the efflux flow from the bed of a reservoir is analyzed. Then, the entrance of falling water wave from the middle and edge sides of the reservoir over a dry bottom is simulated. In order to validate the achieved numerical results for the non-hydrostatic pressure situations a dimensionless number based upon the inflow velocity, the slot length and the falling height is introduced. The obtained results of the defined numerical solver are then compared with the numerical prediction of the STAR-CD which is a commercial Navier-Stokes package. The numerical results demonstrate that the introduced flux-wave solver is able to simulate the falling water waves over the dry-state for a given range of the dimensionless number.

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Due to lower cost compared to field measurement, simulation of sound propagation is considerably favorable for acoustic researchers. One of most optimized methods in this regard is PE (paraboloic Equation), which gives detailed low cost results especially in the low and mid frequencies. On the other hand, most of the human interaction with the water bodies are in the so called shallow water region, where PE is the most common method of acoustic simulation. In this study, effects of environmental parameters on transmission loss are investigated in the range of the scale of few tens of kilometers. The results show subsurface flows and sound speed profile variations in the course of the range, have the least effects and bottom properties, specifically the attenuation factor, are the most effective parameter in the low frequency sound propagation. On the other side, in the range of higher frequencies (more than 1000 Hz), seasonal variation of sound speed profile has the most efficient effect