Self-similarity of the plasma edge fluctuations

Carreras, B. A.; Milligen, B. Ph. van; Pedrosa, M. A.; Balbín, Rosa; Hidalgo, C.; Newman, D. E.; Sánchez, E.; Frances, Maria F.; Garcı́a-Cortés, I.; Bleuel, J.; Endler, M.; Ricardi, C.; Davies, S.; Matthews, G. F.; Martines, E.; Antoni, V.; Latten, A.; Klinger, T.

doi:10.1063/1.873081

Cited by 139 publications

(98 citation statements)

References 31 publications

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“…7 provides information on small flow structures, whereas the slow decaying tail represents a second (larger) structure. This is in good agreement with the analogous observations of Carreras et al (1998). For a shallow pool (Y/D = 2.8 and negative skewness at y/D = 0.35), the sharp decay of the autocorrelation structure corresponds to the description of small flow structures resulting from flow deflection close to the stagnation point.…”

Section: Pressure Distribution For Variable Pool Depthssupporting

confidence: 79%

Impact pressures of turbulent high-velocity jets plunging in pools with flat bottom

2006

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Dynamic pressures created by the impact of high-velocity turbulent jets plunging in a water pool with flat bottom were investigated. Pressure fluctuations were sampled at 1 kHz at the jet outlet and at the pool bottom using piezo-resistive pressure transducers, jet velocities of up to 30 m/s and pool depth to jet diameter ratios from 2.8 to 11.4. The high-velocity jets entrain air in the pool in conditions similar to prototype applications at water release structures of dams. The intermittent character of plunge pool flows was investigated for shallow and deep pools, based on high order moments and time correlations. Maximum intermittency was observed for pool depths at 5.6 jet diameters, which approximate the core development length. Wall pressure skewness was shown to allow identifying the zone of influence of downward and upward moving currents. List of symbols

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Section: Pressure Distribution For Variable Pool Depthssupporting

confidence: 79%

Impact pressures of turbulent high-velocity jets plunging in pools with flat bottom

2006

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“…Various authors have found appealing the idea that in self-organized systems avalanches can be generated on all scales, leading to low-frequency, long-wavelength, selfsimilar correlations. This observation leads to a second thread relating to the possible significance of long-time correlations in certain experimentally observed time series, as reported for example by Carreras et al [10][11][12][13] Carreras 11 suggested that "the measurements [on long-time tails] are consistent with the SOC paradigm of turbulent transport." (He cautioned "However, it does not prove that this model offers the only explanation.…”

Section: Introductionmentioning

confidence: 82%

Self-organized criticality, long-time correlations, and the standard transport paradigm

Krommes

2000

Physics of Plasmas

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Some aspects of low-frequency, long-wavelength fluctuations are considered. A stochastic model is used to show that power-law time correlations need not arise from self-organized criticality. A formula for the frequency spectrum of uncorrelated, overlapping avalanches is shown to be a special case of the spectral balance equation of renormalized statistical turbulence theory. It is argued that there need be no contradiction between the presence of long-time correlations and the existence of local transport coefficients.

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“…generates long-time tails on certain two-time correlations similar to those observed in experiment, 32 as does the dynamically self-consistent Hasegawa-Wakatani model.…”

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confidence: 63%

Renormalized dissipation in the nonconservatively forced Burgers equation

Krommes¹

2000

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A previous calculation [P. H. Diamond and T.-S. Hahm, Phys. Plasmas 2, 3640 (1995)] of the renormalized dissipation in the nonconservatively forced one-dimensional Burgers equation, which encountered a catastrophic long-wavelength divergence ∼ k −3 min , is reconsidered. In the absence of velocity shear, analysis of the eddy-damped quasi-normal Markovian closure predicts only a benign logarithmic dependence on kmin. The original divergence is traced to an inconsistent resonancebroadening type of diffusive approximation, which fails in the present problem. Ballistic scaling of renormalized pulses is retained, but such scaling does not, by itself, imply a paradigm of selforganized criticality. An improved scaling formula for a model with velocity shear is also given. PACS: 52.35. Ra, 05.60.+w In a famous calculation of the "large-distance and longtime properties of a randomly stirred fluid," Forster, Nelson, and Stephen 1 (FNS) analyzed the consequences of various forcing scenarios for the Navier-Stokes equation and, to some extent, Burgers equation. They considered both a conservative forcing (Model A) and a nonconservative one (Model B), 2 and predicted nontrivial properties for the lowfrequency, small-wave-number limits of the two-point correlation and response functions. They did not explicitly consider Model B for Burgers equation; however, that was later studied in considerable detail by Hwa and Kardar 3 (HK). Recently Diamond and Hahm 4 (DH) attempted to use the Burgers Model B in support of a paradigm of self-organized criticality 5,6 (SOC) for plasma transport. In the course of their discussion, they performed a calculation of the renormalized dissipation coefficient η k that describes the mean propagation of small-amplitude pulses with Fourier components k. In the absence of macroscopic velocity shear V , they invoked a wave-number scaling for the turbulent dissipation (η k ∼ k 2 ) that disagreed with that predicted by HK (η k ∼ |k|). As a consequence, they encountered a catastrophic long-wavelength divergence ∼ kmin dq/q 4 , where k min is a minimum wave-number cutoff. Their result for V = 0 also exhibited pathologies. In the present work, I reconsider the calculations. For V = 0, I find only a benign logarithmic divergence and a wave-number scaling in agreement with HK.

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Self-similarity of the plasma edge fluctuations

Cited by 139 publications

References 31 publications

Impact pressures of turbulent high-velocity jets plunging in pools with flat bottom

Impact pressures of turbulent high-velocity jets plunging in pools with flat bottom

Self-organized criticality, long-time correlations, and the standard transport paradigm

Renormalized dissipation in the nonconservatively forced Burgers equation

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