Logarithmic scaling for fluctuations of a scalar concentration in wall turbulence

Mouri, Hideaki; Morinaga, Takeshi; Yagi, Toshimasa; Mori, Kazuyasu

doi:10.1103/physreve.96.063101

Cited by 4 publications

(8 citation statements)

References 29 publications

(58 reference statements)

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“…The experimental value of b w lies between 1.3 and 1.8. 11,12,18 Although the reason for such a discrepancy of b w is not yet known, it appears comparable to uncertainties of b w in observations. 22,23 A criterion is thereby imposed as…”

Section: Data Selectionmentioning

confidence: 58%

“…(2a) from the variance u 2 . [6][7][8][9][10][11][12] Since Taylor's hypothesis has been used in Sec. IV, its effect is discussed here.…”

Section: Resultsmentioning

confidence: 99%

“…The logarithmic law of a variance appears to exist also for fluctuations of the pressure 35 and of the concentration of a passive scalar. 12 To study their energy spectra at a large ratio of δ/z, a field observation would be useful as in our study of k x Φ u .…”

Section: Discussionmentioning

confidence: 99%

“…[6][7][8] Its constant c u appears to take a common value of about 1.3. [6][7][8][9][10][11][12] However, the k −1 x law itself has not been established so far. To derive Eq.…”

Section: Introductionmentioning

confidence: 99%

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Unlikely existence of kx−1 spectral law in wall turbulence: An observation of the atmospheric surface layer

2019

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For wall turbulence, there has been predicted a range of streamwise wavenumbers k x such that the spectral density of streamwise velocity fluctuations is proportional to k −1 x . The existence or nonexistence of this k −1x law is examined here. We observe the atmospheric surface layer over several months, select suitable data, and use them to synthesize the energy spectrum that would represent wall turbulence at a very high Reynolds number. The result is not consistent with the k −1 x law. It is rather consistent with a recent correction to the prediction of a model of energy-containing eddies that are attached to the wall. The reason for these findings is discussed mathematically.

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Section: Data Selectionmentioning

confidence: 58%

“…(2a) from the variance u 2 . [6][7][8][9][10][11][12] Since Taylor's hypothesis has been used in Sec. IV, its effect is discussed here.…”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…[6][7][8] Its constant c u appears to take a common value of about 1.3. [6][7][8][9][10][11][12] However, the k −1 x law itself has not been established so far. To derive Eq.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Unlikely existence of kx−1 spectral law in wall turbulence: An observation of the atmospheric surface layer

2019

Self Cite

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“…IV. It is related to a phenomenology of energy-containing eddies [20][21][22][23][24][25][26][27][28] and also extended to thermally stratified cases via the theory of Monin and Obukhov 1,29 (Sec. V).…”

Section: Introductionmentioning

confidence: 99%

Momentum flux fluctuations in wall turbulence: a formula beyond the law of the wall

Mouri,

Ito

2022

Preprint

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Within wall turbulence, there is a sublayer where the mean wall-normal flux of the streamwise momentum is constant and related to the logarithmic wall-normal profile of the mean streamwise velocity. This relation, i.e., the law of the wall, has been used to estimate the mean stress at the wall surface. However, the momentum flux exhibits large temporal fluctuations. To relate them theoretically to those of the streamwise velocity at the same position from the wall, we consider an orthogonal decomposition of the fluctuations on a plane of the streamwise and wall-normal velocities. Since a large timescale is expected for the component that would dominate the momentum flux, it is singled out by temporal smoothing. The resultant formula is consistent with time-series data of a boundary layer in a wind tunnel. We also extend the formula to thermally stratified cases.

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Estimating instantaneous surface momentum fluxes in boundary layers using a deep neural network

Ito

Mouri

2021

AIP Advances

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Within turbulent boundary layers, the relationship between instantaneous surface momentum fluxes and streamwise velocities is more complicated than that between their ensemble averages described by the law of the wall. Although these fluxes need to be considered in large eddy simulations, the conventional approaches are not feasible. As an alternative, we have developed a deep neural network with the long short-term memory algorithmthat estimates instantaneous fluxes from a sequence of streamwise velocities. The velocities measured in a wind tunnel were used for training and validation. The trained deep neural network successfully estimates the instantaneous surface momentum flux with a suitable running average.

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Logarithmic scaling for fluctuations of a scalar concentration in wall turbulence

Cited by 4 publications

References 29 publications

Unlikely existence of kx−1 spectral law in wall turbulence: An observation of the atmospheric surface layer

Unlikely existence of kx−1 spectral law in wall turbulence: An observation of the atmospheric surface layer

Momentum flux fluctuations in wall turbulence: a formula beyond the law of the wall

Estimating instantaneous surface momentum fluxes in boundary layers using a deep neural network

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