Investigation of flow resistance exerted by rigid emergent vegetation in open channel

D’Ippolito, Antonino; Lauria, Agostino; Alfonsi, Giancarlo; Calomino, Francesco

doi:10.1007/s11600-019-00280-8

Cited by 34 publications

(32 citation statements)

References 51 publications

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“…Additionally, the blending functions were not considered at this stage of simulation. Model coefficients and blending functions are important in cases of flow with a high degree of tribalisation along with additional elements appearing in the analysis, such as the free surface, like in, among others, D'Ippolito et al [56]. In the case under consideration, the simulation results reflect the actual state occurring on the surface of the grinding zone.…”

Section: Mechanicalmentioning

confidence: 99%

Simulation Studies on Centrifugal MQL-CCA Method of Applying Coolant during Internal Cylindrical Grinding Process

2020

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This paper describes simulation studies regarding the application of the centrifugal minimum quantity lubrication (MQL) method simultaneously with the delivery of a compressed cooled air (CCA) stream in the internal cylindrical grinding process. The idea of a new hybrid cooling and lubrication method connecting centrifugal (through a grinding wheel) lubrication by MQL with a CCA stream is described. The methodology of computational fluid dynamics (CFD) simulation studies, as well as the results of numerical simulations, are presented in detail. The aim of the simulations was to determine the most favourable geometrical and kinematic parameters of the system in the context of air-oil aerosol and CCA flow, as well as heat exchange. In the simulation, the variables were the grinding arbor geometrical parameters, the angle of CCA supply line outlets, and the grinding wheel and workpiece peripheral speed. As a result of the simulation studies, the most favourable geometrical parameters were designated, determining the orientation of the ends of the two CCA supply line outlets before and after the grinding zone, the number of openings in the drilled-out grinding arbor, and the influence of the grinding speed on the parameters of the coolant flow and temperature of objects in the grinding zone. In addition, the results of simulation tests made it possible to visualise the velocity vectors of the two-phase coolant flow in a complex system of air-oil aerosol delivery centrifugally through an open structure of a very fast rotating porous layer (grinding wheel), with an additional supply of CCA using an external cold air gun (CAG).

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Section: Mechanicalmentioning

confidence: 99%

Simulation Studies on Centrifugal MQL-CCA Method of Applying Coolant during Internal Cylindrical Grinding Process

2020

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“…0.042 (18) valid for θ = 1.11 rad, a ≥ 4.0 and in the range of 0.30 ≤ a/h ≤ 0.61 and 1.15 ≤ b/a ≤ 3.55, with determination coefficient R 2 = 0.927, maximum percent error e max = 3.6%, and average percent error e average = 1.3%. Figure 6 shows the values of the discharge coefficients as a function of the relative opening a/h for the weir inclination angle θ = 56.…”

Section: Resultsmentioning

confidence: 98%

“…By means of numerical simulations the 27 runs of the Series 3 (Table 3) were carried out (considering the maximum values of h and Q) by solving the three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations [17][18][19] in conservative form (the fluid is incompressible and viscous, Einstein summation convention applies to repeated indices, i, j = 1, 2, 3):…”

Section: Numerical Simulationsmentioning

confidence: 99%

Discharge Coefficients for Sluice Gates Set in Weirs at Different Upstream Wall Inclinations

Lauria

Calomino

Alfonsi

et al. 2020

Water

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Laboratory experiments and numerical simulations are performed to measure discharge coefficients in the case of a gate located on the upstream wall of a weir for flood storage. The effect of the gate slope and the side contraction have been taken into account. The study was first performed experimentally, when three series of tests were carried out with (and without) a broad crested weir located under the gate, at different values of the inclination angle of the weir upstream wall, and at different values of the shape ratio and the relative opening. In order to provide useful suggestions for those involved in sluice gate construction and management, three equations were obtained based on multiple regression, relating the discharge coefficient to different parameters that characterize the phenomenon at hand, separating the case when the broad-crested weir was present. Then numerical simulations were executed by means of the Reynolds-averaged Navier–Stokes (RANS) equations with the k-ε turbulence closure model and in conjunction with the volume of fluid (VOF) method, to validate the numerical results against the experimental and to possibly investigate phenomena not caught by the experimental measurements. Simulated discharges were very close to the observed ones showing that the proposed three-dimensional numerical procedure is a favorable option to correctly reproduce the phenomenon.

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“…Following the Boussinesq approximation [20,21], the eddy viscosity is set as a function of the turbulent kinetic energy and the energy dissipation rate. In order to establish a relation between the Reynolds stress and the mean-flow quantities, the k-omega SST model [22] is utilized as follows (see also [23,24]):…”

Section: Methodsmentioning

confidence: 99%

“…The closure coefficients of the selected model are β * = 9/100, σ k1 = 0.85, σ ω1 = 0.5, σ ω2 = 0.856, α 1 = 5/9, α 2 = 0.44, β 1 = 3/40. The k-ω SST model generally performs well in complex flow cases (see, e.g., [21,22,25]).…”

Section: Methodsmentioning

confidence: 99%

Flow Pressure Behavior Downstream of Ski Jumps

Lauria

Alfonsi

Tafarojnoruz

2020

Fluids

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Ski jump spillways are frequently implemented to dissipate energy from high-speed flows. The general feature of this structure is to transform the spillway flow into a free jet up to a location where the impact of the jet creates a plunge pool, representing an area for potential erosion phenomena. In the present investigation, several tests with different ski jump bucket angles are executed numerically by means of the OpenFOAM® digital library, taking advantage of the Reynolds-averaged Navier–Stokes equations (RANS) approach. The results are compared to those obtained experimentally by other authors as related to the jet length and shape, obtaining physical insights into the jet characteristics. Particular attention is given to the maximum pressure head at the tailwater. Simple equations are proposed to predict the maximum dynamic pressure head acting on the tailwater, as dependent upon the Froude number, and the maximum pressure head on the bucket. Results of this study provide useful suggestions for the design of ski jump spillways in dam construction.

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Investigation of flow resistance exerted by rigid emergent vegetation in open channel

Cited by 34 publications

References 51 publications

Simulation Studies on Centrifugal MQL-CCA Method of Applying Coolant during Internal Cylindrical Grinding Process

Simulation Studies on Centrifugal MQL-CCA Method of Applying Coolant during Internal Cylindrical Grinding Process

Discharge Coefficients for Sluice Gates Set in Weirs at Different Upstream Wall Inclinations

Flow Pressure Behavior Downstream of Ski Jumps

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