Re-examination of the Reynolds-Number-Effect on the Mean Flow Quantities in a Smooth Wall Turbulent Boundary Layer.

Osaka, Hideo; Kameda, Takatsugu; Mochizuki, Shinsuke

doi:10.1299/jsmeb.41.123

Cited by 49 publications

(35 citation statements)

References 10 publications

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“…At x / h＝-20, regardless of the installation of the splitter plate, the value of the dominant term, -(h / U e 3 ) uv∂U/∂y (term A) is about 0.001, while the magnitude of the term of additional rates-of-strain -(h / U e 3 ) u 2 ∂U/∂x (term B), is less than 1% of the former one. This signifies the good two-dimensionality of the present flow fields at this position similar to the well-achieved turbulent boundary layer under the zero pressure gradient of Osaka et al (6) . Thus, the contribution of the latter term is negligible as in an ordinary turbulent boundary layer.…”

Section: Production Terms Of Turbulent Energysupporting

confidence: 81%

“…The Reynolds number based on the momentum thickness R θ for the present study is about 3000 near the trailing edge (for detail, with a single-hot-wire probe, see Figure 8(b) in reference (1)). Independent of the installation of the splitter plate, at x / h＝-20 and -10, the turbulent intensity u rms / U e and v rms / U e and the Reynolds shear stress are kept similar to that of a fully-developed turbulent boundary layer on the smooth wall under the zero pressure gradient (hereafter ZPG, R θ ＝2980), as in Osaka et al (6) , as shown by the dash-dotted line. The solid line in these figures indicates the result of Klebanoff (7) for reference.…”

Section: Turbulent Quantity Distribution In Boundary Layer Near Trailmentioning

confidence: 86%

“…This coincides with the result of Rinoie et al (4) on a backward-facing step. Here, based on the result of Osaka et al (6) on flow over a smooth wall under the zero pressure gradient, turbulent quantities decrease at the height of the inner layer of the developed boundary layer as R θ increases. This tendency coincides with that of Westphal et al (12) in contrast to the results from a present long flat plate (1) and that of Rinoie et al (4) on a backward-facing step, subjected to a favorable pressure gradient.…”

Section: Comparison With Related Flow Fieldsmentioning

confidence: 99%

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Effects of Splitter Plates on Turbulent Quantities on a Boundary Layer Developing on a Flat Plate near the Trailing Edge

Jodai

Ichimiya

Osaka

2011

JFST

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An experimental investigation was made on a turbulent boundary layer near the trailing edge on a long flat plate with a blunt trailing edge. The flow was controlled by an additional splitter plate attached to the trailing edge along the wake center line. The length of the splitter plate, l, was varied from 0.3 to 3 times the trailing edge thickness, h. Measurement of fluctuating velocity was made under the freestream zero pressure gradient. Almost independent of the installation of the splitter plate, the turbulent intensity and the Reynolds shear stress in the inner layer decreased when approaching the trailing edge of the flat plate (x / h＝0), compared with that in the fully-developed turbulent boundary layer under the zero pressure gradient. The only exception was the distribution at x / h＝0 near the wall in the case without the splitter plate (l / h＝0), where the degree of the decrease in u rms / U e was relatively small, and v rms / U e and -uv / U e 2 were larger than those of the zero pressure gradient. The effect of l / h on turbulent quantities was shown just upstream of the trailing edge upon close comparison, and was classified into two groups: l / h＜1 and l / h≧1. The tendency of the turbulent energy production terms approaching x / h＝0 coincided with the decrease in the streamwise turbulent intensity and in the Reynolds shear stress.

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Section: Production Terms Of Turbulent Energysupporting

confidence: 81%

Section: Turbulent Quantity Distribution In Boundary Layer Near Trailmentioning

confidence: 86%

Section: Comparison With Related Flow Fieldsmentioning

confidence: 99%

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Effects of Splitter Plates on Turbulent Quantities on a Boundary Layer Developing on a Flat Plate near the Trailing Edge

Jodai

Ichimiya

Osaka

2011

JFST

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“…This careful attention to the fluid acceleration effect can also be also found in experiments on turbulent boundary layers with a zero pressure gradient (Osaka et al, 1998;de Graaff and Eaton, 2000;Schultz and Flack, 2003;Schultz and Flack, 2007;Volino et al, 2009;Volino et al, 2011;Örlü and Schlatter, 2013). The acceleration of the free stream can be reduced to produce a turbulent boundary layer with a negligible pressure gradient.…”

Section: Introductionmentioning

confidence: 61%

“…In previous experiments in which boundary layer flows were measured, the fluid acceleration effect was quantified by the acceleration parameter K = (ν/U 2 ) (dU/dx) (de Graaff and Eaton, 2000). Another definition based on the streamwise pressure gradient has also been used in previous experiments (e.g., Osaka et al, 1998;Örlü and Schlatter, 2013). This definition requires the acceleration parameter to be sufficiently small in an observed turbulent boundary layer with zero pressure gradient.…”

Section: Resultsmentioning

confidence: 99%

Validation scheme for small effect of wind tunnel blockage on decaying grid-generated turbulence

Suzuki

Mochizuki

2016

JFST

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This paper proposes a validation scheme for the effect of wind tunnel blockage on decaying grid-generated turbulence. This validation scheme was derived from the governing equations of the k-ϵ model. Analytical solutions for the validation scheme were derived by introducing a model of the difference between the rate of change of the effect of fluid acceleration on the turbulent kinetic energy and that of the effect on its dissipation. The derived solutions include a decay exponent that excludes the acceleration effect, a parameter characterizing the acceleration, the initial anisotropy, and the model coefficient of the k-ϵ model, and can be quantified by parameters which can be known. The physical meaning of the model was clarified. The derived solutions and model were confirmed to be accurate through numerical simulation. An equation for the decay exponent, which is also affected by the fluid acceleration, was developed using the derived solutions. This scheme was applied to the examination of the reduced fluid acceleration effect in a moderate-sized wind tunnel to measure the grid-generated turbulence. The fluid acceleration effect in the wind tunnel was confirmed to be small using the derived equations. The decay characteristics of the grid-generated turbulence in the wind tunnel were measured and were found to agree with those obtained in previous experiments.

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Non-Equilibrium and Equilibrium Boundary Layers without Pressure Gradient

Kameda

Mochizuki

Osaka

2008

IUTAM Symposium on Computational Physics and New Perspectives in Turbulence

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Re-examination of the Reynolds-Number-Effect on the Mean Flow Quantities in a Smooth Wall Turbulent Boundary Layer.

Cited by 49 publications

References 10 publications

Effects of Splitter Plates on Turbulent Quantities on a Boundary Layer Developing on a Flat Plate near the Trailing Edge

Effects of Splitter Plates on Turbulent Quantities on a Boundary Layer Developing on a Flat Plate near the Trailing Edge

Validation scheme for small effect of wind tunnel blockage on decaying grid-generated turbulence

Non-Equilibrium and Equilibrium Boundary Layers without Pressure Gradient

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