Abstract. During the floods, the effects of sediment transport in river beds are particulary significant and can be studied through the evolution of the water-sediment layer which moves in the lower part of a flow, named "moving layer". Moving layer variations along rivers lead to depositions and erosions and are typically unsteady, but are often tackled with expressions developed for steady (equilibrium) conditions. In this paper, we develop an expression for the moving layer in unsteady conditions and calibrate it with experimental data. During laboratory tests, we have in fact reproduced a rapidly changing unsteady flow by the erosion of a granular steep slope. Results have shown a clear tendency of the moving layer, for fixed discharges, toward equilibrium conditions. Knowing the equilibrium achievement has presented many difficulties, being influenced by the choice of the equilibrium expression and moreover by the estimation of the parameters involved (for example friction angle). Since we used only data relevant to hyper-concentrated mono-dimensional flows for the calibration -occurring for slope gradients in the range 0.03-0.20 -our model can be applied both on open channels and on embankments/dams, providing that the flows can be modelled as mono-dimensional, and that slopes and applied shear stress levels fall within the considered ranges.
After the publication of the flood directive hazard and risk maps, risk assessment and risk evaluation became useful tools to set priorities for flood management and for countermeasure financing. Regione Piemonte, in collaboration with Politecnico di Torino and University of Turin, proposed a procedure for risk assessment (named IRP model, Index of Proportional Risk), already applied in different case studies. The comparison among the obtained results and the collected data on damages recorded during the recent 2016 flood in Piemonte region showed the effectiveness of the IRP procedure for the quantitative assessment of direct damages. The IRP model can also be usefully applied to the revision and the updating of flood directive risk maps and to assess the cost/benefit ratio of the designed countermeasures (National Repository for Soil defense (Re.N.Di.S.) procedure).
This paper is focused on the study of the sloshing in the fuel tank of vehicles. As well known, fluid dynamic in an automotive fuel tank have to be studied and optimized to allow the correct fuel suction in all driving conditions, prevent undesired slosh noise and limit its influence on fuel vapor formation and management. Experimentation to predict the sloshing with a good accuracy depends on the ability to replace real working parameters and conditions like accelerations, decelerations, slope variations and rotations.
This paper shows results obtained studying the sloshing inside a reference tank with computational fluid-dynamic and experimental approaches.
The test bench for automotive fuel tank, employed in this analysis, has been designed by Moog Inc. on specification from Fiat Chrysler Automobiles and it is aimed at covering the wider possible range of dynamic conditions. It basically consists of a hexapod, which uses six independent actuators arranged in three triangles and connecting a base and a top platform, thus allowing all six DOFs. Above the top platform is mounted a tilt table with two additional actuators, to extend pitch and roll envelope, thus the name of “8-DOF bench”.
A dedicated CFD model has been built up using a CFD commercial code. The model has been integrated with the multiphase tool in order to correctly reply the real free surface.
Results, numerical and experimental, have been post-processed with Matlab® comparing percentage gaps of the free surfaces each other. The comparison has shown a good agreement.
This research is the result of a scientific collaboration between the Industrial Engineering Department of University of Naples Federico II and FCA Fiat Chrysler Automobiles.
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