Delayed correlation between turbulent energy injection and dissipation

Pearson, B. R.; Yousef, T. A.; Haugen, Nils Erland L.; Brandenburg, Axel; Krogstad, Per‐Åge

doi:10.1103/physreve.70.056301

Cited by 51 publications

(68 citation statements)

References 15 publications

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“…In wind tunnel turbulence one usually expresses the energy flux in units of a quantity C ǫ = u ′3 /L, where u ′ = u rms / √ 3 is the one-dimensional rms velocity and L = 3π/4k f is the customary definition of the integral scale. The standard result of C ǫ ≈ 0.5 (Pearson et al 2004) corresponds then to ǫ ≈ 0.04k f u 3 rms . Comparing the normalized energy fluxes for linear and monochromatic random forcings we see hardly any differences.…”

Section: Figmentioning

confidence: 99%

Kinetic helicity decay in linearly forced turbulence

Brandenburg

Petrosyan

2012

Astron Nachr

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The decay of kinetic helicity is studied in numerical models of forced turbulence using either an externally imposed forcing function as an inhomogeneous term in the equations or, alternatively, a term linear in the velocity giving rise to a linear instability. The externally imposed forcing function injects energy at the largest scales, giving rise to a turbulent inertial range with nearly constant energy flux while for linearly forced turbulence the spectral energy is maximum near the dissipation wavenumber. Kinetic helicity is injected once a statistically steady state is reached, but it is found to decay on a turbulent time scale regardless of the nature of the forcing and the value of the Reynolds number.

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Section: Figmentioning

confidence: 99%

Kinetic helicity decay in linearly forced turbulence

Brandenburg

Petrosyan

2012

Astron Nachr

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“…The value of the shear constants has been extensively discussed by Breech et al [2008]; we take C sh Z = C sh W = 1. Also, in keeping with recent studies, we adopt de Kármán-Taylor constants a = 2b = 0.25 and~= 2~= 0.25 [Pearson et al, 2004;Breech et al, 2009]. The form used for pickup ion driving,…”

Section: Numerical Solutionsmentioning

confidence: 99%

Transport of solar wind fluctuations: A two-component model

et al. 2011

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[1] We present a new model for the transport of solar wind fluctuations which treats them as two interacting incompressible components: quasi-two-dimensional turbulence and a wave-like piece. Quantities solved for include the energy, cross helicity, and characteristic transverse length scale of each component, plus the proton temperature. The development of the model is outlined and numerical solutions are compared with spacecraft observations. Compared to previous single-component models, this new model incorporates a more physically realistic treatment of fluctuations induced by pickup ions and yields improved agreement with observed values of the correlation length, while maintaining good observational accord with the energy, cross helicity, and temperature.

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“…This observation has also been called the "zeroth law of turbulence", as Kolmogorov's hypotheses assume that the mean energy dissipation rate is independent of the viscosity at high Reynolds numbers (Frisch, 1995;Pearson et al, 2004). Figure 12 shows the current measurements of C ε as a function of Reynolds number.…”

Section: Large-scale Turbulencementioning

confidence: 99%

Schneefernerhaus as a mountain research station for clouds and turbulence

Risius

Lorenzo

et al. 2015

Atmos. Meas. Tech.

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Abstract. Cloud measurements are usually carried out with airborne campaigns, which are expensive and are limited by temporal duration and weather conditions. Ground-based measurements at high-altitude research stations therefore play a complementary role in cloud study. Using the meteorological data (wind speed, direction, temperature, humidity, visibility, etc.) collected by the German Weather Service (DWD) from 2000 to 2012 and turbulence measurements recorded by multiple ultrasonic sensors (sampled at 10 Hz) in 2010, we show that the Umweltforschungsstation Schneefernerhaus (UFS) located just below the peak of Zugspitze in the German Alps, at a height of 2650 m, is a well-suited station for cloud-turbulence research. The wind at UFS is dominantly in the east-west direction and nearly horizontal. During the summertime (July and August) the UFS is immersed in warm clouds about 25 % of the time. The clouds are either from convection originating in the valley in the east, or associated with synoptic-scale weather systems typically advected from the west. Air turbulence, as measured from the second-and third-order velocity structure functions that exhibit well-developed inertial ranges, possesses Taylor microscale Reynolds numbers up to 10 4 , with the most probable value at ∼ 3000. In spite of the complex topography, the turbulence appears to be nearly as isotropic as many laboratory flows when evaluated on the "Lumley triangle".

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Delayed correlation between turbulent energy injection and dissipation

Cited by 51 publications

References 15 publications

Kinetic helicity decay in linearly forced turbulence

Kinetic helicity decay in linearly forced turbulence

Transport of solar wind fluctuations: A two-component model

Schneefernerhaus as a mountain research station for clouds and turbulence

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