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The present work investigates the effect of the flow profile induced by an inlet condition on the roll-wave evolution in turbulent clear-water flows. The study employs theoretical and numerical analyses. Firstly, the influence of the inlet condition on the spatial evolution of a single perturbation in a hypercritical flow is examined through the expansion near a wavefront analysis. The results show that an accelerated unperturbed profile reduces the disturbance spatial growth. A decelerated profile causes an increase. The effect of the flow profile on the spatial evolution of roll-wave trains is then numerically investigated solving the Saint Venant equations with a second-order Runge-Kutta Total Variation Diminishing (TVD) Finite Volume scheme. The numerical simulations comply with the analytical results for the initial and transition phases of the roll-wave development. The unperturbed profile influences even the roll-waves statistical characteristics in the final stage, with a more evident effect in case of accelerated profiles. The influence of the flow profile should be therefore accounted for in the formulation of predictive criteria for roll-waves appearance based on the estimation of the disturbance spatial growth rate.

The paper addresses the prediction of roll-waves occurrence in mud-flows. The spatial growth of a point-wise disturbance is analytically described, based on the linearized flow model of a Herschel and Bulkley fluid, in the neighborhood of an initial uniform base condition. The theoretical achievements allow to generalize to mud-flows the minimum channel criterion commonly used for the prediction of roll-waves in clear-water. The applicability of the criterion is discussed through the comparison with literature laboratory data concerning unstable flows without rollwaves.

Dikes and levees are encountered very often along rivers. They are crucial as defence structures for flow channelization, protecting population and properties from floods as well as against lateral riverbed migration. However, the combination of their aging and increased exposition to extreme hydrological events may cause these structures to breach, and subsequently to fail. Understanding the dynamics of breaching is very important for developing adequate countermeasures, for civil protection initiatives and for land use planning. Recent literature shows many studies concerning, both from experimental and numerical point of views, frontal dike breaching. Based on several evidences, it is well assessed that depth-integrated numerical models can successfully reproduce this kind of phenomenon (e.g. Greco et al., 2012). Recently, Rifai et al. (2017) investigated a different setup in which the embankment is parallel to the main channel flow and thus a lateral breaching occurs. It is worth noting this scheme resembles real-world situation of levees breaching along a river. In present paper, the capability of depth-integrated approaches in reproducing such tests is investigated. Numerical results obtained with different models are compared against experiments from both the qualitative and quantitative point of views. Considerations about the applicability of depth-integrated models in real world situation of lateral breaching of dikes and levees are also drawn.

This research aims at studying the intrinsic vulnerability of groundwater to diffuse environmental pollutants in the Muravera coastal agricultural area of Sardinia, Italy. The area faces contamination risks arising from agricultural practices, especially the use of fertilizers, pesticides, and various chemicals that can seep into the groundwater. The study examined the interplay among hydrological elements, including soil characteristics, groundwater depth, climate conditions, land use, and aquifer properties. To do that, the outcomes of FLOWS 1D physically-based agrohydrological model were analyzed in parallel with those of the overlay-and-index model SINTACS, in a sort of reciprocal benchmarking. By using FLOWS, water movement and solute transport in the unsaturated zone were simulated by, respectively, solving the Richard Equation (RE) and the Advection-Dispersion equation (ADE). As such, this model allowed to account for the role of soil hydraulic and hydro-dispersive properties variability in determining the travel times of a conservative solute through the soil profile to the groundwater. For FLOWS simulations, a complete dataset was used as input, including soil horizons, soil physical and hydraulic properties of 36 soil profiles, average annual depth to groundwater table at each soil profile (ranging from 1 to 50 meters), and climatic temporal series data on rainfall and evapotranspiration. Detailed analyses of travel times for the movement of 25, 50, 75, and 100% of the solute mass to reach groundwater were conducted, revealing that the depth to groundwater predominantly influences vulnerability. This result was coherent with SINTACS vulnerability map due to the large impact of the depth to groundwater on SINTACS analysis. [ABSTRACT FROM AUTHOR]

Agricultural tractors and their implements are at the basis of modern farming. Besides propulsion, in such system, most of the mechanical actuations are performed with a fluid power system that is highly power-dense and versatile, but has a low energy efficiency. This article first describes the challenges of the state-of-the-art hydraulic system that cause poor efficiency. Afterward, it proposes and demonstrates a solution that can significantly increase such efficiency without affecting the cost and functionality of the overall hydraulic control system. The proposed solution is based on a peculiar control approach to the hydraulic supply units that power the implement functions through the hydraulic remote connections. The approach is based on an impressed-pressure control methodology, as opposed to the traditional impressed flow method used in off-road machinery. The result is that the typical energy-inefficient pressure saturation conditions that often occur in common vehicles are mitigated and brought to a more efficient state. To support the development of the technology, the research takes into consideration the circuit of a 400-hp tractor and a 16-row planter. A simulation model of the hydraulic system of the two vehicles was implemented and validated against experiments. The model was then utilized to estimate the reduction in the energy consumption achieved by the proposed solution. Lab tests and field experiments of the proposed solutions applied to the reference tractor and planter system confirmed an overall 18% energy efficiency improvement. [ABSTRACT FROM AUTHOR]