1,721,028 research outputs found
Effect of spatial rainfall distribution on runoff volumes and peak discharges for a large urban watershed
No full textSimulations of fifteen real storms recorded at eight rain gauges, located in Milan, were carried out in order to test the sensitivity of the spatial distribution of the rain on runoff volumes and peak discharges. For this purpose a large urban watershed was selected and spatially uniform and non uniform rainfalls were input in a previously calibrated model. Results of simulations show that an uniform storm pattern can lead to significant underpredictions of rainfall volumes and, especially, of peak discharges. -Author
Sull’onda conseguente al crollo di uno sbarramento in alveo pendente: soluzione perturbativa in assenza di resistenza
No full textIl contributo delle casse di espansione alla protezione idraulica dei territori di pianura
No full textDopo una breve introduzione nella quale vengono sinteticamente illustrati scopi,
tipologie e funzionamento delle casse di espansione, si descrivono in dettaglio i principali
esempi di realizzazione in Emilia. Richiamate le equazioni che governano il fenomeno di laminazione
ed i metodi di risoluzione, si approfondisce il comportamento delle casse sul fiume
Secchia e sul torrente Parma, valutando l’efficienza delle stesse al variare della sollecitazione
idrologica. Si analizza infine il comportamento della cassa sul torrente Parma in occasione
dell’evento di piena del 13 ottobre 2014, ricostruendo le portate in ingresso e simulando mediante
un modello 2D alle acque basse cosa sarebbe successo nell’ipotesi di assenza della stessa.
Dai risultati si evince che la cassa di espansione ha sicuramente salvato il centro storico di Parma
da una grave alluvione
Internal boundary conditions for a GPU-accelerated 2D shallow water model: Implementation and applications
No full textFlood propagation in rivers is strongly influenced by the presence of bridges and other hydraulic structures. Among the available approaches for including these elements in numerical models, the adoption of Internal Boundary Conditions (IBC), given its ability to capture backwater, is suitable for field-scale analyses for flood hazard assessment. In this paper, the implementation of internal boundary conditions in the two-dimensional shallow water code named “PARFLOOD” is presented. The application to experimental and real test cases shows that the proposed IBC model can handle both low and high flow conditions for bridges, while being flexible for other types of structures (e.g. flow-through dams). Moreover, the model is computationally efficient (physical/computational time ratio around 20–30 for domains with ~106 cells), thanks to the code parallelization on GPU
Soluzione adimensionale per un problema di Dam-Break in alveo prismatico pendente, in assenza di resistenze
No full text
Scour around circular piers: espermental test on the existence of a final equilibiurm situation
No full textNumerical treatment of a discontinuous top surface in 2D shallow water mixed flow modeling
Full text linkThis paper presents a numerical strategy based on shallow water equations (SWE) coupled with the 2D Preissmann slot model to handle a ceiling step discontinuity in finite volume schemes for mixed flow modeling. In practice, a typical situation would be a closed structure, such as a bridge or culvert, which induces a sudden vertical flow constriction and may even run partly or totally full in high flow conditions. In such case, both the inlet and outlet of the structure involve a discontinuity in the top elevation. This special singularity is topologically represented by inserting a fictitious cell between 2 adjacent computational cells characterized by sharply different ceiling elevation. The 2D SWE are solved by means of a well-balanced quasi-conservative Godunov-type numerical scheme based on the Slope Limiter Centered (SLIC) scheme. The flow variables at each boundary of the fictitious cell are reconstructed by adopting the cross-sectional shape of the adjoining cell. Accordingly, the dynamic effect of the structure deck on the flow is suitably modeled, and the C-property for a stationary solution is rigorously satisfied, even when the closed structure is partially full. The capability of the numerical scheme is verified by comparison with both novel analytical solutions of 1D Riemann problems with a ceiling step discontinuity and experimental data of steady and unsteady mixed flows available in literature. Finally, a real-scale application to a multiple arch bridge is presented. The results show that the method is robust and effective in predicting the 2D features induced by a crossing structure on the flow dynamics
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