Detached eddy simulation of the nonaerated skimming flow over a stepped spillway

Juan Pablo Toro, Fabián A. Bombardelli, Joongcheol Paik

Resultado de la investigación: Contribución a la publicaciónArticle

Resumen

The unsteady three-dimensional (3D), nonaerated, skimming flow over a stepped spillway is investigated by means of a detached eddy simulation (DES). Special emphasis is placed on the description of the instantaneous velocity and vorticity fields on the step cavities, as well as on the 3D, long-term, average flow structure at a Reynolds number of approximately 105. Mean-flow velocities obtained from simulations on both relatively-coarse and fine meshes at different locations in the spillway are in very good agreement with particle image velocimetry (PIV) data published elsewhere. Nondimensional profiles of turbulence intensity and Reynolds stresses are also close to data, although numerical values are larger than the experimental counterparts. Snapshots of velocity vectors reveal that the flow near the pseudobottom is continuously flapping, and that it intermittently interacts with ejections of positive vorticity emanating from the cavities. As a result of the interaction between the shear flow and the 3D cavity flow, patches of positive and negative vorticity are carried away downstream, eventually interacting with the free surface. It is also found that the ratios of redistribution among components (terms) of the turbulent kinetic energy (TKE) at the step edges are very similar to those universal values for the intermediate region of open-channel flows. It is additionally shown that large-scale structures extracted from isosurfaces of the Q-criterion correspond primarily to well-organized, randomly-distributed thin tubes of vorticity. The instantaneous flow field revealed in this paper is considered crucial for modeling the even more complex aerated region.

Idioma originalEnglish
Número de artículo04017032
PublicaciónJournal of Hydraulic Engineering
Volumen143
Número de edición9
Identificadores de objetos digitales
EstadoPublished - 1 sep 2017

Huella dactilar

vorticity
Vorticity
spillway
cavity
simulation
Spillways
eddy
open channel flow
shear flow
flow structure
Reynolds number
flow velocity
flow field
kinetic energy
turbulence
modeling
Open channel flow
Flow structure
Shear flow
Flow velocity

Keywords

    ASJC Scopus subject areas

    • Civil and Structural Engineering
    • Water Science and Technology
    • Mechanical Engineering

    Citar esto

    Toro, Juan Pablo; Bombardelli, Fabián A.; Paik, Joongcheol / Detached eddy simulation of the nonaerated skimming flow over a stepped spillway.

    En: Journal of Hydraulic Engineering, Vol. 143, N.º 9, 04017032, 01.09.2017.

    Resultado de la investigación: Contribución a la publicaciónArticle

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    abstract = "The unsteady three-dimensional (3D), nonaerated, skimming flow over a stepped spillway is investigated by means of a detached eddy simulation (DES). Special emphasis is placed on the description of the instantaneous velocity and vorticity fields on the step cavities, as well as on the 3D, long-term, average flow structure at a Reynolds number of approximately 105. Mean-flow velocities obtained from simulations on both relatively-coarse and fine meshes at different locations in the spillway are in very good agreement with particle image velocimetry (PIV) data published elsewhere. Nondimensional profiles of turbulence intensity and Reynolds stresses are also close to data, although numerical values are larger than the experimental counterparts. Snapshots of velocity vectors reveal that the flow near the pseudobottom is continuously flapping, and that it intermittently interacts with ejections of positive vorticity emanating from the cavities. As a result of the interaction between the shear flow and the 3D cavity flow, patches of positive and negative vorticity are carried away downstream, eventually interacting with the free surface. It is also found that the ratios of redistribution among components (terms) of the turbulent kinetic energy (TKE) at the step edges are very similar to those universal values for the intermediate region of open-channel flows. It is additionally shown that large-scale structures extracted from isosurfaces of the Q-criterion correspond primarily to well-organized, randomly-distributed thin tubes of vorticity. The instantaneous flow field revealed in this paper is considered crucial for modeling the even more complex aerated region.",
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    Detached eddy simulation of the nonaerated skimming flow over a stepped spillway. / Toro, Juan Pablo; Bombardelli, Fabián A.; Paik, Joongcheol.

    En: Journal of Hydraulic Engineering, Vol. 143, N.º 9, 04017032, 01.09.2017.

    Resultado de la investigación: Contribución a la publicaciónArticle

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    N2 - The unsteady three-dimensional (3D), nonaerated, skimming flow over a stepped spillway is investigated by means of a detached eddy simulation (DES). Special emphasis is placed on the description of the instantaneous velocity and vorticity fields on the step cavities, as well as on the 3D, long-term, average flow structure at a Reynolds number of approximately 105. Mean-flow velocities obtained from simulations on both relatively-coarse and fine meshes at different locations in the spillway are in very good agreement with particle image velocimetry (PIV) data published elsewhere. Nondimensional profiles of turbulence intensity and Reynolds stresses are also close to data, although numerical values are larger than the experimental counterparts. Snapshots of velocity vectors reveal that the flow near the pseudobottom is continuously flapping, and that it intermittently interacts with ejections of positive vorticity emanating from the cavities. As a result of the interaction between the shear flow and the 3D cavity flow, patches of positive and negative vorticity are carried away downstream, eventually interacting with the free surface. It is also found that the ratios of redistribution among components (terms) of the turbulent kinetic energy (TKE) at the step edges are very similar to those universal values for the intermediate region of open-channel flows. It is additionally shown that large-scale structures extracted from isosurfaces of the Q-criterion correspond primarily to well-organized, randomly-distributed thin tubes of vorticity. The instantaneous flow field revealed in this paper is considered crucial for modeling the even more complex aerated region.

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