Evaluation of mixing length in a planar mixing layer based on shear-induced vorticity

Keh-Chin Chang, Chiuan Ting Li

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

1 Citation (Scopus)

Abstract

An incompressible turbulent planar mixing layer is composed of two different flow types in its flow field, namely a shear layer in the central region and two free streams in the outer high- and low-speed sides. Shear layer, which is of shear turbulence, is formed right after the trailing edge of the splitter plate and develops streamwisely through successively distinct regions, namely the near field (developing) region and the self-preserving (developed) region. A new definition of the mixing length (lω) is proposed on the basis of an effectively pure shear-induced vorticity component (ΩSH) by means of a triple decomposition method, that is, l ω = yH - yL where yH and yL are the two transverse positions, at which |ΩSH| normalized with the maximum ∂U/∂y at the trailing edge is equal to 0.06, in the high- and low-speed free stream sides, respectively. It is shown that the linear growth rate of lω along streamwise distance can be now used as one of the necessary and sufficient conditions for justifying the achievement of the self-preserving state in turbulent mixing layer.

Original languageEnglish
Title of host publication39th AIAA Fluid Dynamics Conference
Publication statusPublished - 2009
Event39th AIAA Fluid Dynamics Conference - San Antonio, TX, United States
Duration: 2009 Jun 222009 Jun 25

Other

Other39th AIAA Fluid Dynamics Conference
CountryUnited States
CitySan Antonio, TX
Period09-06-2209-06-25

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Vorticity
Flow fields
Turbulence
Decomposition

All Science Journal Classification (ASJC) codes

  • Engineering (miscellaneous)
  • Aerospace Engineering

Cite this

Chang, K-C., & Li, C. T. (2009). Evaluation of mixing length in a planar mixing layer based on shear-induced vorticity. In 39th AIAA Fluid Dynamics Conference [2009-4172]
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Chang, K-C & Li, CT 2009, Evaluation of mixing length in a planar mixing layer based on shear-induced vorticity. in 39th AIAA Fluid Dynamics Conference., 2009-4172, 39th AIAA Fluid Dynamics Conference, San Antonio, TX, United States, 09-06-22.

Evaluation of mixing length in a planar mixing layer based on shear-induced vorticity. / Chang, Keh-Chin; Li, Chiuan Ting.

39th AIAA Fluid Dynamics Conference. 2009. 2009-4172.

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

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AU - Li, Chiuan Ting

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N2 - An incompressible turbulent planar mixing layer is composed of two different flow types in its flow field, namely a shear layer in the central region and two free streams in the outer high- and low-speed sides. Shear layer, which is of shear turbulence, is formed right after the trailing edge of the splitter plate and develops streamwisely through successively distinct regions, namely the near field (developing) region and the self-preserving (developed) region. A new definition of the mixing length (lω) is proposed on the basis of an effectively pure shear-induced vorticity component (ΩSH) by means of a triple decomposition method, that is, l ω = yH - yL where yH and yL are the two transverse positions, at which |ΩSH| normalized with the maximum ∂U/∂y at the trailing edge is equal to 0.06, in the high- and low-speed free stream sides, respectively. It is shown that the linear growth rate of lω along streamwise distance can be now used as one of the necessary and sufficient conditions for justifying the achievement of the self-preserving state in turbulent mixing layer.

AB - An incompressible turbulent planar mixing layer is composed of two different flow types in its flow field, namely a shear layer in the central region and two free streams in the outer high- and low-speed sides. Shear layer, which is of shear turbulence, is formed right after the trailing edge of the splitter plate and develops streamwisely through successively distinct regions, namely the near field (developing) region and the self-preserving (developed) region. A new definition of the mixing length (lω) is proposed on the basis of an effectively pure shear-induced vorticity component (ΩSH) by means of a triple decomposition method, that is, l ω = yH - yL where yH and yL are the two transverse positions, at which |ΩSH| normalized with the maximum ∂U/∂y at the trailing edge is equal to 0.06, in the high- and low-speed free stream sides, respectively. It is shown that the linear growth rate of lω along streamwise distance can be now used as one of the necessary and sufficient conditions for justifying the achievement of the self-preserving state in turbulent mixing layer.

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Chang K-C, Li CT. Evaluation of mixing length in a planar mixing layer based on shear-induced vorticity. In 39th AIAA Fluid Dynamics Conference. 2009. 2009-4172