Toward a dynamical systems approach for the understanding of turbulent flow pulsations between subchannels

Elia Merzari, H. Ninokata

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Tight fuel lattices are characterized by quasi-periodical flow oscillations between subchannels, as first observed by Hooper ([1]). The above mentioned phenomena are of inherently unstable nature and, even if no conclusive theoretical study on the subject have been published, the evidence shown to this point suggests that the oscillations are connected to interactions between eddy structures of turbulent flows in adjacent subchannels ([2]). This coherent structures travel in the direction of homogeneous turbulence, in a fashion that strongly recalls the Von-Karman Vortex Street ([3]). Analogous behaviours have been observed for arrays of arbitrarily shaped channels ([4]), within certain range of the geometric parameters. Numerical simulation of these phenomena is challenging, and a completely satisfactory explanation of their cause is not available. A modelling for these phenomena is at least problematic to achieve since they are turbulence driven. This paper aims to address the use of POD (Proper Orthonormal Decomposition) to reduce the Navier-Stokes equation to a set of ordinary differential equations ([5]).The set of ODE is solved numerically, and a series of comparison with experimental and numerical data is offered, in order to test the predicting capability of the models proposed.

Original languageEnglish (US)
Title of host publicationProceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12
StatePublished - Dec 1 2007
Event12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12 - Pittsburgh, PA, United States
Duration: Sep 30 2007Oct 4 2007

Publication series

NameProceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12

Other

Other12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12
CountryUnited States
CityPittsburgh, PA
Period9/30/0710/4/07

Fingerprint

turbulent flow
dynamical systems
Turbulent flow
Dynamical systems
Turbulence
Karman vortex street
homogeneous turbulence
oscillations
Ordinary differential equations
Navier-Stokes equation
travel
Navier Stokes equations
Vortex flow
differential equations
turbulence
vortices
Decomposition
decomposition
causes
Computer simulation

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Nuclear and High Energy Physics

Cite this

Merzari, E., & Ninokata, H. (2007). Toward a dynamical systems approach for the understanding of turbulent flow pulsations between subchannels. In Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12 (Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12).
Merzari, Elia ; Ninokata, H. / Toward a dynamical systems approach for the understanding of turbulent flow pulsations between subchannels. Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12. 2007. (Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12).
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abstract = "Tight fuel lattices are characterized by quasi-periodical flow oscillations between subchannels, as first observed by Hooper ([1]). The above mentioned phenomena are of inherently unstable nature and, even if no conclusive theoretical study on the subject have been published, the evidence shown to this point suggests that the oscillations are connected to interactions between eddy structures of turbulent flows in adjacent subchannels ([2]). This coherent structures travel in the direction of homogeneous turbulence, in a fashion that strongly recalls the Von-Karman Vortex Street ([3]). Analogous behaviours have been observed for arrays of arbitrarily shaped channels ([4]), within certain range of the geometric parameters. Numerical simulation of these phenomena is challenging, and a completely satisfactory explanation of their cause is not available. A modelling for these phenomena is at least problematic to achieve since they are turbulence driven. This paper aims to address the use of POD (Proper Orthonormal Decomposition) to reduce the Navier-Stokes equation to a set of ordinary differential equations ([5]).The set of ODE is solved numerically, and a series of comparison with experimental and numerical data is offered, in order to test the predicting capability of the models proposed.",
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Merzari, E & Ninokata, H 2007, Toward a dynamical systems approach for the understanding of turbulent flow pulsations between subchannels. in Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12. Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12, 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12, Pittsburgh, PA, United States, 9/30/07.

Toward a dynamical systems approach for the understanding of turbulent flow pulsations between subchannels. / Merzari, Elia; Ninokata, H.

Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12. 2007. (Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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N2 - Tight fuel lattices are characterized by quasi-periodical flow oscillations between subchannels, as first observed by Hooper ([1]). The above mentioned phenomena are of inherently unstable nature and, even if no conclusive theoretical study on the subject have been published, the evidence shown to this point suggests that the oscillations are connected to interactions between eddy structures of turbulent flows in adjacent subchannels ([2]). This coherent structures travel in the direction of homogeneous turbulence, in a fashion that strongly recalls the Von-Karman Vortex Street ([3]). Analogous behaviours have been observed for arrays of arbitrarily shaped channels ([4]), within certain range of the geometric parameters. Numerical simulation of these phenomena is challenging, and a completely satisfactory explanation of their cause is not available. A modelling for these phenomena is at least problematic to achieve since they are turbulence driven. This paper aims to address the use of POD (Proper Orthonormal Decomposition) to reduce the Navier-Stokes equation to a set of ordinary differential equations ([5]).The set of ODE is solved numerically, and a series of comparison with experimental and numerical data is offered, in order to test the predicting capability of the models proposed.

AB - Tight fuel lattices are characterized by quasi-periodical flow oscillations between subchannels, as first observed by Hooper ([1]). The above mentioned phenomena are of inherently unstable nature and, even if no conclusive theoretical study on the subject have been published, the evidence shown to this point suggests that the oscillations are connected to interactions between eddy structures of turbulent flows in adjacent subchannels ([2]). This coherent structures travel in the direction of homogeneous turbulence, in a fashion that strongly recalls the Von-Karman Vortex Street ([3]). Analogous behaviours have been observed for arrays of arbitrarily shaped channels ([4]), within certain range of the geometric parameters. Numerical simulation of these phenomena is challenging, and a completely satisfactory explanation of their cause is not available. A modelling for these phenomena is at least problematic to achieve since they are turbulence driven. This paper aims to address the use of POD (Proper Orthonormal Decomposition) to reduce the Navier-Stokes equation to a set of ordinary differential equations ([5]).The set of ODE is solved numerically, and a series of comparison with experimental and numerical data is offered, in order to test the predicting capability of the models proposed.

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Merzari E, Ninokata H. Toward a dynamical systems approach for the understanding of turbulent flow pulsations between subchannels. In Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12. 2007. (Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12).