Large-Eddy Simulation in Hydraulics

Rodi, W.; Constantinescu, George; Stoesser, Thorsten

doi:10.1201/b15090

Cited by 133 publications

(127 citation statements)

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“…Prediction of the flow field can be established by performing economical RANS simulations with standard k-ε models. Though, it should be kept in mind that RANS simulations have difficulties in coping adequately with complex flow phenomena, such as large-scale turbulence structures Rodi, Conatantinescu, & Stoesser, 2013), and one should strive to avoid installing the instrument in or close to recirculation zones.…”

Section: Resultsmentioning

confidence: 99%

“…In the last decades the computer power has kept increasing, and this has revealed that RANS models have limitations, especially when applied for coherent structures. Recent development has provided methods such as Large Eddy Simulations (LES), where the large scales are resolved and the small scales are model (Rodi, Conatantinescu, & Stoesser, 2013). Another recent method is the Detached Eddy Simulation (DES), which is a hybrid modeling approach where RANS closure is applied in some parts of the flow field and LES in others (CD-adapco, 2009).…”

Section: Engineering Applications Of Computational Fluid Mechanicsmentioning

confidence: 99%

“…As a consequent, the number of grid points are needed for most practical hydraulic engineering problems becomes so large that computational resources necessary exceed the capacity of available computers (Rodi, Conatantinescu, & Stoesser, 2013). A common way to avoid massive computations is to use a turbulence model based on the Reynolds average Navier-Stokes Equations -a so called RANS model.…”

Section: Engineering Applications Of Computational Fluid Mechanicsmentioning

confidence: 99%

“…Hence, RANS models are most applicable for practical employment, because they are economical in terms of computational and memory resources. Though, one should be aware that RANS simulations have limitations, especially when dealing with large-scale turbulence structures (Rodi, Conatantinescu, & Stoesser, 2013).…”

Section: Engineering Applications Of Computational Fluid Mechanicsmentioning

confidence: 99%

See 3 more Smart Citations

Calibration of Horizontal Acoustic Doppler Current profilers by three dimensional CFD simulations

Bråtveit

Olsen

2015

Engineering Applications of Computational Fluid Mechanics

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This study presents a calibration method of horizontal acoustic Doppler current profilers (H-ADCP), based on 3D Computational Fluid Dynamics (CFD) simulations. Rigidly mounted H-ACCPs are currently used to continuously monitor water discharges. In this study three instruments were employed at separate sites in an unlined rock-blasted hydro power tunnel. The total discharge in the tunnel was predicted by fitting numerical and measured velocity profiles. The accuracy of the method was evaluated by comparing discharge predictions to results obtained by thermodynamic efficiency measurements. This study shows that 3D CFD simulations not only can be used to accurately calibrate H-ADCP, but also to assess the flow conditions at the locations of installation. An average error of 2% was obtained for the tunnel stretch that possessed the most uniform flow. However, the precision of the discharge estimates were confined by the CFD code's capability to correctly resolve the flow pattern.

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Section: Resultsmentioning

confidence: 99%

Section: Engineering Applications Of Computational Fluid Mechanicsmentioning

confidence: 99%

Section: Engineering Applications Of Computational Fluid Mechanicsmentioning

confidence: 99%

Section: Engineering Applications Of Computational Fluid Mechanicsmentioning

confidence: 99%

See 2 more Smart Citations

Calibration of Horizontal Acoustic Doppler Current profilers by three dimensional CFD simulations

Bråtveit

Olsen

2015

Engineering Applications of Computational Fluid Mechanics

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“…The diffusive terms are approximated by fourth-order central differences while convective fluxes in the momentum and level-set equations are approximated using a fifth-order weighted, essentially non-oscillatory (WENO) scheme. Rodi, Constantinescu, and Stoesser (2013) state that the accuracy and credibility of a code can be justified by the use of high-order spatial discretization schemes together with sufficiently fine grids. A fractional-step method is used with a Runge-Kutta predictor and the multigrid method is used as a corrector of the final step when solving the Poisson pressure-correction equation.…”

Section: Numerical Framework and Computational Considerationsmentioning

confidence: 99%

Free surface flow over square bars at intermediate relative submergence

McSherry

Chua

Stoesser

et al. 2018

Journal of Hydraulic Research

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Results from large-eddy simulations and complementary flume experiments of turbulent open channel flows over bed-mounted square bars at intermediate submergence are presented. Scenarios with two bar spacings, corresponding to transitional and k-type roughness, and three flow rates, are investigated. Good agreement is observed between the simulations and the experiments in terms of mean free surface elevations and mean streamwise velocities. Contours of simulated time-averaged streamwise, streamfunction and turbulent kinetic energy are presented and these reveal the effect of the roughness geometry on the water surface response. The analysis of the vertical distribution of the streamwise velocity shows that in the lowest submergence cases no logarithmic layer is present, whereas in the higher submergence cases some evidence of such a layer is observed. For several of the flows moderate to significant water surface deformations are observed, including weak and/or undular hydraulic jumps which affect significantly to the overall streamwise momentum balance. Reynolds shear stress, form-induced stress and form drag are analysed with reference to the momentum balance to assess their contributions to the total hydraulic resistance of these flows. The results show that form-induced stresses are dominant at the water surface and can contribute significantly to the overall drag, but the total resistance in all cases is dominated by form drag due to the presence of the bars.

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Mixing dynamics at the confluence of two large rivers undergoing weak density variations

Ramón

Armengol

Dolz

et al. 2014

J. Geophys. Res. Oceans

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Simulations of tracer experiments conducted with a three-dimensional primitive-equation hydrodynamic and transport model are used to understand the processes controlling the rate of mixing between two rivers (Ebro and Segre), with distinct physical and chemical properties, at their confluence, upstream of a meandering reservoir (Ribarroja reservoir). Mixing rates downstream of the confluence are subject to hourly scale oscillations, driven partly by changes in inflow densities and also as a result of turbulent eddies that develop within the shear layer between the confluent rivers and near a dead zone located downstream of the confluence. Even though density contrasts are low-at most O(10 21 ) kg m 23 difference among sources-and almost negligible from a dynamic point of view-compared with inertial forces-they are important for mixing. Mixing rates between the confluent streams under weakly buoyant conditions can be of up to 40% larger than those occurring under neutrally buoyant conditions. The buoyancy effects on mixing rates are interpreted as the result of changes in the contact area available for mixing (distortion of the mixing layer). For strong density contrasts, though, when the contact area between the streams becomes nearly horizontal, larger density differences between streams will lead to weaker mixing rates, as a result of the stabilizing effect of vertical density gradients.

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Large-Eddy Simulation in Hydraulics

Cited by 133 publications

References 0 publications

Calibration of Horizontal Acoustic Doppler Current profilers by three dimensional CFD simulations

Calibration of Horizontal Acoustic Doppler Current profilers by three dimensional CFD simulations

Free surface flow over square bars at intermediate relative submergence

Mixing dynamics at the confluence of two large rivers undergoing weak density variations

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