Numerical Modeling of Flow Over a Rectangular Broad-Crested Weir with a Sloped Upstream Face

Abstract

The objective of this study was to evaluate the effect of the upstream angle on flow over a trapezoidal broad-crested weir based on numerical simulations using the open-source toolbox OpenFOAM. Eight trapezoidal broad-crested weir configurations with different upstream face angles (θ = 10°, 15°, 22.5°, 30°, 45°, 60°, 75°, 90°) were investigated under free-flow conditions. The volume-of-fluid (VOF) method and two turbulence models (the standard k-ε model and the SST k-w model) were employed in the numerical simulations. The numerical results were compared with the experimental results obtained from published papers. The root mean square error (RMSE) and the mean absolute percent error (MAPE) were used to evaluate the accuracy of the numerical results. The statistical results show that RMSE and MAPE values of the standard k-ε model are 0.35–0.67% and 0.50–1.48%, respectively; the RMSE and MAPE values of the SST k-w model are 0.25–0.66% and 0.55–1.41%, respectively. Additionally, the effects of the upstream face angle on the flow features, including the discharge coefficient and the flow separation zone, were also discussed in the present study.

Simulation Analysis of Combined Flow over and under Semi-Cylindrical Structure

“…Free code source software "OpenFOAM" is used to simulate flow over broad crested weir with inclined upstream face, the comparison between the results of two turbulence models, the standard k-ε model; and the SST k-w show good prediction of flow profile. The predicted area of separation zone by SST k-w model is larger than that predicted by standard k-e model and the coefficient of discharge decreases as the angle of the upstream face increases [10]. Twodimensional finite element model (CCHE2D) is validated on the physical model of river bend with and without weir structure, the two-dimensional model is imposed to evaluate the roughness of the bed which is employed in three-dimensional model (CCHE3D).The models show that the flow in river bend is typical with a superelevation in the bend without weir structure and also there is a high water surface zone built up at a centre part of the upstream face of the weir [11].…”

Hydraulic analysis of a compound weir (triangular-rectangular) simulated with computational fluid dynamics (CFD)

“…The basis of an adjusted and adequate development to the physical conditions of a computational model is the numerical scheme that approximately solves the equations that describe the flow. Because it is a two-phase (water-air) and free surface flow, it is assigned to the multiphase VOF model and the turbulence K-ε (Launder & Spalding, 1974) model because it is the most complete simple method with the lowest computational cost to simulate turbulence demonstrating its advantage in confined and internal flows (Fernández, 2012) and in free-surface flows (Chanel & Doering, 2008;Olsen, Nils, & Kjellesvig, 1998;Jiang, Diao, Sun, & Ren, 2018).…”

Assessment of CFD turbulence models for free surface flow simulation and 1-D modelling for water level calculations over a broad-crested weir floodway

“…e coe cient of discharge of broad-crested weirs has been experimentally studied by Fritz and Hager (1998) without considering the e ect of the weir's upstream-facing slope. e impact of the weir's upstream-facing slope has been studied by Sargison andPercy (2009), Shaymaa et al (2015), Aysegul andMustafa (2016), andJiang et al (2018). It was agreed by all researchers that the coe cient of discharge increases when decreasing the angle of the weir upstreamfacing slope.…”