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Parameter governing the far-field features of round jets

Parameter governing the far-field features of round jets This study is inspired by the observation and hypothesis that the spreading and decay behaviors of a jet directly depend on the momentum-mixing mechanism between the jet and surrounding fluid. This mixing behavior is dictated by the kinematic viscosity ν for a laminar jet, which can be dramatically enhanced in a turbulent flow and is represented by the eddy viscosity ɛ . Similarly, pulsation in a synthetic jet is identified as another mechanism for enhancing mixing, which can be captured by an enhanced eddy viscosity beyond what is observed in a corresponding turbulent continuous jet. To this end, an effective-eddy-viscosity concept is proposed to model any excitation of a jet that could result in enhanced mixing beyond what is predicted by the kinematic viscosity. Our previous study found that ɛ is actuator dependent and its relationship with the spreading or decay behavior of a jet is not obvious. To remove the actuator dependence, this study performs a dimensional analysis to relate the spreading and decay behaviors to a scaled effective eddy viscosity ɛ / K ( K is the momentum flux). This quantity physically represents a competition between the radial diffusion and the axial convection of the jet axial momentum. The experimental results confirm that ɛ / K governs the spreading and decay rates of the far field for any round jets. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review Fluids American Physical Society (APS)

Parameter governing the far-field features of round jets

Physical Review Fluids , Volume 1 (6): 9 – Oct 10, 2016

Parameter governing the far-field features of round jets

Physical Review Fluids , Volume 1 (6): 9 – Oct 10, 2016

Abstract

This study is inspired by the observation and hypothesis that the spreading and decay behaviors of a jet directly depend on the momentum-mixing mechanism between the jet and surrounding fluid. This mixing behavior is dictated by the kinematic viscosity ν for a laminar jet, which can be dramatically enhanced in a turbulent flow and is represented by the eddy viscosity ɛ . Similarly, pulsation in a synthetic jet is identified as another mechanism for enhancing mixing, which can be captured by an enhanced eddy viscosity beyond what is observed in a corresponding turbulent continuous jet. To this end, an effective-eddy-viscosity concept is proposed to model any excitation of a jet that could result in enhanced mixing beyond what is predicted by the kinematic viscosity. Our previous study found that ɛ is actuator dependent and its relationship with the spreading or decay behavior of a jet is not obvious. To remove the actuator dependence, this study performs a dimensional analysis to relate the spreading and decay behaviors to a scaled effective eddy viscosity ɛ / K ( K is the momentum flux). This quantity physically represents a competition between the radial diffusion and the axial convection of the jet axial momentum. The experimental results confirm that ɛ / K governs the spreading and decay rates of the far field for any round jets.

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Publisher
American Physical Society (APS)
Copyright
©2016 American Physical Society
Subject
RAPID COMMUNICATIONS; Turbulent flows
ISSN
2469-990X
eISSN
2469-990X
DOI
10.1103/PhysRevFluids.1.062401
Publisher site
See Article on Publisher Site

Abstract

This study is inspired by the observation and hypothesis that the spreading and decay behaviors of a jet directly depend on the momentum-mixing mechanism between the jet and surrounding fluid. This mixing behavior is dictated by the kinematic viscosity ν for a laminar jet, which can be dramatically enhanced in a turbulent flow and is represented by the eddy viscosity ɛ . Similarly, pulsation in a synthetic jet is identified as another mechanism for enhancing mixing, which can be captured by an enhanced eddy viscosity beyond what is observed in a corresponding turbulent continuous jet. To this end, an effective-eddy-viscosity concept is proposed to model any excitation of a jet that could result in enhanced mixing beyond what is predicted by the kinematic viscosity. Our previous study found that ɛ is actuator dependent and its relationship with the spreading or decay behavior of a jet is not obvious. To remove the actuator dependence, this study performs a dimensional analysis to relate the spreading and decay behaviors to a scaled effective eddy viscosity ɛ / K ( K is the momentum flux). This quantity physically represents a competition between the radial diffusion and the axial convection of the jet axial momentum. The experimental results confirm that ɛ / K governs the spreading and decay rates of the far field for any round jets.

Journal

Physical Review FluidsAmerican Physical Society (APS)

Published: Oct 10, 2016

There are no references for this article.