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Journal ArticleDOI

Performance assessment of OpenFOAM and FLOW-3D in the numerical modeling of a low Reynolds number hydraulic jump

TL;DR: A comparative performance analysis of the CFD platforms OpenFOAM and FLOW-3D is presented, focusing on a 3D swirling turbulent flow: a steady hydraulic jump at low Reynolds number, where both CFD codes had good behavior, but special care is required with swirling flows.
Abstract: A comparative performance analysis of the CFD platforms OpenFOAM and FLOW-3D is presented, focusing on a 3D swirling turbulent flow: a steady hydraulic jump at low Reynolds number. Turbulence is treated using RANS approach RNG k-e. A Volume Of Fluid (VOF) method is used to track the air-water interface, consequently aeration is modeled using an Eulerian-Eulerian approach. Structured meshes of cubic elements are used to discretize the channel geometry. The numerical model accuracy is assessed comparing representative hydraulic jump variables (sequent depth ratio, roller length, mean velocity profiles, velocity decay or free surface profile) to experimental data. The model results are also compared to previous studies to broaden the result validation. Both codes reproduced the phenomenon under study concurring with experimental data, although special care must be taken when swirling flows occur. Both models can be used to reproduce the hydraulic performance of energy dissipation structures at low Reynolds numbers. Two CFD models: OpenFOAM and FLOW-3D for hydraulic jump in low Reynolds numbers.Representative variables are compared for the two CFD results and experimental data.The model results are also compared to previous studies with good agreement.Both CFD codes had good behavior, but special care is required with swirling flows.A quantification of both models accuracy relating to studied variables is proposed.
Citations
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26 Aug 2004
TL;DR: In this article, a three-dimensional computational fluid dynamics model with the renormalization group k-e turbulence scheme was developed to investigate the effects of ambient wind direction on flow and dispersion around a group of buildings.
Abstract: A three-dimensional computational fluid dynamics model with the renormalization group k–e turbulence scheme is developed. The model developed is used to investigate the effects of ambient wind direction on flow and dispersion around a group of buildings. According to the ambient wind direction, three flow patterns are identified in a view of the characteristics of the mean flow circulation generated in street canyons. In the first flow pattern, a portal vortex generated behind the east wall of the upwind building is symmetric about the center of the street canyon. In the second flow pattern, a portal vortex is also generated behind the east wall of the upwind building, but its horizontal axis is not perpendicular to the ambient wind direction. In the third flow pattern, the footprints of a portal vortex are located behind both the east and north walls of the upwind building. When the incident wind angle is 45°, flow is diagonally symmetric behind the upwind building. As the incident wind angle increases, pollutant escape from the street canyons decreases. Except for the case where the ambient wind direction is perpendicular to the buildings, pollutants are trapped in the portal vortex, thus exhibiting high concentration there.

250 citations

Journal ArticleDOI
TL;DR: In this article, a new formulation for the prediction of free surface dynamics related to the turbulence occurring nearby is proposed, which can be used to compute the inception of self-aeration in high velocity flows like those occurring in hydraulic structures.

57 citations

Journal ArticleDOI
TL;DR: In this paper, numerical models of the flow in the non-aerated region of stepped spillways have been developed using diverse turbulence closures and discretization schemes implemented in two CFD codes: OpenFOAM and FLOW-3D®.

56 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used numerical software to establish the shear sliding model of bolt rock masses and analyzed the influence of the setting conditions of the bolt on the anchor strength of a bolt rock mass.
Abstract: Bolt reinforcement is a standard reinforcement method for jointed rock masses. However, regarding rock anchoring, the mechanical characteristics of the joint surface, as well as the angle between the bolt and the joint sliding surface, are important factors that affect rock support. Therefore, to understand the influence of a set angle, length, normal load, and other conditions that affect the shear strength of bolt joints, this study uses numerical software to establish the shear sliding model of bolt rock masses and analyzes the influence of the setting conditions of the bolt on the shear strength of a bolt rock mass, which can be done by changing the setting method of the bolt and normal mechanical conditions of the sliding surface. The results show that the shear strength of the anchor joint is not affected after the anchor reaches a certain length. The angle of the anchor strongly influences the shear strength of the anchor joint, and the shear strength curve is V-shaped, where the anchor angle is less than 90°. Moreover, the shear strength curve indicates a downward trend when the anchor angle is greater than 90°, and the shear strength of the anchorage joint increases with the increase of the normal load. Under the same anchor length (4 cm) in the anchor angle and shear strength coordinate system, the shear strength curve of the single anchor is above the shear strength curve of the double anchor, which is exclusively in the local anchor angle section under the condition of a large normal load and a large anchor angle. The shear strength curve of the double anchor is above the shear strength curve of the single anchor.

55 citations

Journal ArticleDOI
24 Dec 2018-Water
TL;DR: It is expected that with the increase in the computational capabilities, the RANS-based numerical studies of the hydraulic jump will approach the prototype scale problems, which are of great relevance for hydraulic engineers, while the application at this scale of the most advanced tools, such as LES and DNS, is still beyond expectations for the foreseeable future.
Abstract: During the past two decades, hydraulic jumps have been investigated using Computational Fluid Dynamics (CFD). The second part of this two-part study is devoted to the state-of-the-art of the numerical simulation of the hydraulic jump. First, the most widely-used CFD approaches, namely the Reynolds-Averaged Navier–Stokes (RANS), the Large Eddy Simulation (LES), the Direct Numerical Simulation (DNS), the hybrid RANS-LES method Detached Eddy Simulation (DES), as well as the Smoothed Particle Hydrodynamics (SPH), are introduced pointing out their main characteristics also in the context of the best practices for CFD modeling of environmental flows. Second, the literature on numerical simulations of the hydraulic jump is presented and discussed. It was observed that the RANS modeling approach is able to provide accurate results for the mean flow variables, while high-fidelity methods, such as LES and DES, can properly reproduce turbulence quantities of the hydraulic jump. Although computationally very expensive, the first DNS on the hydraulic jump led to important findings about the structure of the hydraulic jump and scale effects. Similarly, application of the Lagrangian meshless SPH method provided interesting results, notwithstanding the lower research activity. At the end, despite the promising results still available, it is expected that with the increase in the computational capabilities, the RANS-based numerical studies of the hydraulic jump will approach the prototype scale problems, which are of great relevance for hydraulic engineers, while the application at this scale of the most advanced tools, such as LES and DNS, is still beyond expectations for the foreseeable future. Knowledge of the uncertainty associated with RANS modeling may allow the careful design of new hydraulic structures through the available CFD tools.

46 citations

References
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Book
01 Jan 1955
TL;DR: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part, denoted as turbulence as discussed by the authors, and the actual flow is very different from that of the Poiseuille flow.
Abstract: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part. These actual flows show a special characteristic, denoted as turbulence. The character of a turbulent flow is most easily understood the case of the pipe flow. Consider the flow through a straight pipe of circular cross section and with a smooth wall. For laminar flow each fluid particle moves with uniform velocity along a rectilinear path. Because of viscosity, the velocity of the particles near the wall is smaller than that of the particles at the center. i% order to maintain the motion, a pressure decrease is required which, for laminar flow, is proportional to the first power of the mean flow velocity. Actually, however, one ob~erves that, for larger Reynolds numbers, the pressure drop increases almost with the square of the velocity and is very much larger then that given by the Hagen Poiseuille law. One may conclude that the actual flow is very different from that of the Poiseuille flow.

17,321 citations

Journal ArticleDOI
TL;DR: In this paper, the concept of a fractional volume of fluid (VOF) has been used to approximate free boundaries in finite-difference numerical simulations, which is shown to be more flexible and efficient than other methods for treating complicated free boundary configurations.

11,567 citations


"Performance assessment of OpenFOAM ..." refers background or methods in this paper

  • ...Nomenclature Acronyms CFD Computational fluid dynamics DNS Direct numerical simulation LES Large eddy simulation RANS Reynolds averaged NaviereStokes RNG Re-normalization group VOF Volume of fluid FVM Finite volume method TKE Turbulent kinetic energy FFT Fast Fourier transform ACF Auto correlation function PSD Power spectrum density Sub- and super-indices 1 Relative to upstream of hydraulic jump 2 Relative to downstream of hydraulic jump * Relative to classic hydraulic jump Exp Relative to experimental results t Relative to turbulence s Relative to flow recirculation min Relative to minimum value max Relative to maximum value Symbols xixjxk Cartesian coordinates uiujuk Velocity components X Dimensionless longitudinal coordinate Z Dimensionless vertical coordinate U Dimensionless velocity t Time p Pressure r Density m Dynamic viscosity y Kinematic viscosity g Acceleration of gravity f Frequency fb Body forces Q q Water flow rate Specific flow rate y Flow depth H Hydraulic head DH Hydraulic head drop G Water free surface profile b Channel width Y Sequent depth h Hydraulic jump efficiency x0 Hydraulic jump toe position xr Roller end position xj Hydraulic jump end position Lr Roller length Lj Hydraulic jump length a Water fraction k Turbulent kinetic energy ε Turbulent kinetic energy dissipation rate Pk Production of TKE C1εC2εC3εsksε k-ε turbulence model parameters d Distance to wall ut Shear velocity xþyþ Dimensionless wall coordinates x Flow property g TKE decay factor s TKE threshold r2 Coefficient of determination uc Compression velocity Dx Mesh element size u Flow aspect ratio d0 Distance from streambed to maximum velocity Fluid mechanics numbers Fr Froude number Re Reynolds number We Weber number Cr Courant number...

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  • ...A Volume Of Fluid (VOF) method is used to track the airewater interface, consequently aeration is modeled using an EulerianeEulerian approach....

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  • ...FLOW-3D is a commercial software package based as well on the FVM, developed by FlowScience, Inc. FLOW-3D includes the Volume of Fluid (VOF) method as originally described by Hirt and Nichols (1981)....

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  • ...Despite the VOF method can be applied to variable-density flows (Chen and Li, 1998), in this particular case NaviereStokes equations are used in their incompressible form (this assumption can generally be done in flows where the Mach number is Ma 0.3)....

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  • ...An additional transport equation must be approximated to determine the value of the fluid fraction throughout the computational domain (Hirt and Nichols, 1981):...

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Book
01 Jan 1993
TL;DR: In this paper, the authors proposed a compressible ecoulement for compressible ECCs, based on the disquette reference record created on 2005-11-18, modified on 2016-08-08.
Abstract: Keywords: ecoulement : compressible Note: + disquette Reference Record created on 2005-11-18, modified on 2016-08-08

7,023 citations


"Performance assessment of OpenFOAM ..." refers background in this paper

  • ...An extended description of RANS equations and turbulence closures can be found in Pope (2000) and Wilcox (1998)....

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  • ...882 that the maximum errors take place in the swirling region, where turbulence models are most prone to fail in reproducing the flow behavior (Wilcox, 1998)....

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  • ...It is therefore expectable that the maximum errors take place in the swirling region, where turbulence models are most prone to fail in reproducing the flow behavior (Wilcox, 1998)....

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Book
01 Jan 1959
TL;DR: This book discusses the development of Uniform Flow and its applications, as well as the theory and analysis of open channel flow, and the design of channels for Uniform Flow.
Abstract: Chapter 1: Basic PrinciplesChapter 2: Open-Channel Flow and its ClassificationsChapter 3: Open Channels and Their PropertiesChapter 4: Energy and Momentum PrinciplesChapter 5: Critical Flow: Its Computation and ApplicationsChapter 6: Uniform FlowChapter 7: Development of Uniform Flow and Its FormulasChapter 8: Computation of Uniform FlowChapter 9: Design of Channels for Uniform FlowChapter 10: Theoretical Concepts of Boundary LayerChapter 11: Surface RoughnessChapter 12: Velocity Distribution and Instability of Uniform FlowChapter 13: Gradually Varied FlowChapter 14: Theory and AnalysisChapter 15: Methods of ComputationChapter 16: Practical ProblemsChapter 17: Spatially Varied FlowChapter 18: Rapidly Varied FlowChapter 19: Flow Over SpillwaysChapter 20: Hydraulic Jump and its Use as Energy DissipatorChapter 21: Flow in Channels of Non-Linear AlignmentChapter 22: Flow Through Nonprismatic Channel SectionsChapter 23: Unsteady FlowChapter 24: Gradually Varied Unsteady FlowChapter 25: Rapidly Varied Unsteady Flow Flood RoutingAppendices

5,013 citations


"Performance assessment of OpenFOAM ..." refers background or methods in this paper

  • ...Lower values of Fr1 lead to undular or transition jumps, characterized by lower efficiencies and formation of waves of irregular period (Fawer, 1937; Chow, 1959; Chanson and Montes, 1995)....

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  • ...One of the main reasons is that hydraulic jumps are the most used method to dissipate energy in hydraulic structures (Chow, 1959)....

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Journal ArticleDOI
TL;DR: The implementation of various types of turbulence modeling in a FOAM computational-fluid-dynamics code is discussed, and calculations performed on a standard test case, that of flow around a square prism, are presented.
Abstract: In this article the principles of the field operation and manipulation (FOAM) C++ class library for continuum mechanics are outlined. Our intention is to make it as easy as possible to develop reliable and efficient computational continuum-mechanics codes: this is achieved by making the top-level syntax of the code as close as possible to conventional mathematical notation for tensors and partial differential equations. Object-orientation techniques enable the creation of data types that closely mimic those of continuum mechanics, and the operator overloading possible in C++ allows normal mathematical symbols to be used for the basic operations. As an example, the implementation of various types of turbulence modeling in a FOAM computational-fluid-dynamics code is discussed, and calculations performed on a standard test case, that of flow around a square prism, are presented. To demonstrate the flexibility of the FOAM library, codes for solving structures and magnetohydrodynamics are also presented with appropriate test case results given. © 1998 American Institute of Physics.

3,987 citations


"Performance assessment of OpenFOAM ..." refers background in this paper

  • ...OpenFOAM (2011) is a freely available open source platform containing several Cþþ libraries and applications which can numerically solve continuum mechanics problems (Weller et al., 1998)....

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