Multiscale anisotropic fluctuations in sheared turbulence with multiple states

Iyer, Kartik P.; Bonaccorso, Fabio; Biferale, Luca; Toschi, Federico

doi:10.1103/physrevfluids.2.052602

Cited by 21 publications

(12 citation statements)

References 47 publications

(73 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such abrupt transitions between turbulent states in a more general sense are a remarkable feature of fluid turbulence and have received much recent interest, being observed in various different flow settings, e.g. in torque measurements of Taylor-Couette and Von Kármán flows (Ravelet et al 2004;Saint-Michel et al 2013;Huisman et al 2014), in states of stochastically forced 2-D and 3-D turbulence (Bouchet & Simonnet 2009;Iyer et al 2017;Bouchet, Rolland & Simonnet 2019) and in reversals of the large-scale dynamics in thin layers (Sommeria 1986;Michel et al 2016;Dallas, Seshasayanan & Fauve 2020). These types of abrupt transition are surmised to play an important role in, for example, climate research (Weeks et al 1997;Jackson & Wood 2018;Herbert, Caballero & Bouchet 2020) and in understanding the geomagnetic reversal (Berhanu et al 2007;Pétrélis et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Discontinuous transitions towards vortex condensates in buoyancy-driven rotating turbulence

et al. 2022

View full text Add to dashboard Cite

Using direct numerical simulations of rotating Rayleigh–Bénard convection, we explore the transitions between turbulent states from a three-dimensional (3-D) flow state towards a quasi-2-D condensate known as the large-scale vortex (LSV). We vary the Rayleigh number $Ra$ as control parameter and study the system response (strength of the LSV) in terms of order parameters, assessing the energetic content in the flow and the upscale energy flux. By sensitively probing the boundaries of the region of existence of the LSV in parameter space, we find discontinuous transitions and we identify the presence of a hysteresis loop as well as a memoryless abrupt growth dynamics. We show furthermore that the creation of the condensate state coincides with a discontinuous transition of the energy transport into the largest mode of the system.

show abstract

Section: Introductionmentioning

confidence: 99%

Discontinuous transitions towards vortex condensates in buoyancy-driven rotating turbulence

et al. 2022

View full text Add to dashboard Cite

show abstract

“…the isotropic sector (δ r θ) p 0 extracted from the SO(3) decomposition [44,45] of S p θ (r), is only a function of scalar separation r [46]. For scale r in the inertial range, η K ≪ r ≪ ℓ, where ℓ is the integral scale of the velocity field, taken as r/η K ∈ [30, 300] [41], (δ r θ) p 0 are found to follow power laws, (δ r θ) p 0 ∼ r ζ θ p , where ζ θ p denote the pth order scaling exponents.…”

mentioning

confidence: 99%

Steep Cliffs and Saturated Exponents in Three-Dimensional Scalar Turbulence

et al. 2018

Self Cite

View full text Add to dashboard Cite

The intermittency of a passive scalar advected by three-dimensional Navier-Stokes turbulence at a Taylor-scale Reynolds number of 650 is studied using direct numerical simulations on a 4096 3 grid; the Schmidt number is unity. By measuring scalar increment moments of high orders, while ensuring statistical convergence, we provide unambiguous evidence that the scaling exponents saturate to 1.2 for moment order beyond about 12, indicating that scalar intermittency is dominated by the most singular shock-like cliffs in the scalar field. We show that the fractal dimension of the spatial support of steep cliffs is about 1.8, whose sum with the saturation exponent value of 1.2 adds up to the space dimension of 3, thus demonstrating a deep connection between the geometry and statistics in turbulent scalar mixing. The anomaly for the fourth and sixth order moments is comparable to that in the Kraichnan model for the roughness exponent of 2/3.

show abstract

“…where • denotes space, time and angle (or spherical) averages [34,35]. The angle averaging is performed to obtain the isotropic sector of S (n,m) (r) from its SO(3) expansion [36,37].…”

Section: Numerical Method Flow Parameters and Definitionsmentioning

confidence: 99%

Scaling exponents saturate in three-dimensional isotropic turbulence

Iyer,

Sreenivasan,

Yeung

2020

Preprint

Self Cite

View full text Add to dashboard Cite

From a database of direct numerical simulations of homogeneous and isotropic turbulence, generated in periodic boxes of various sizes, we extract the spherically symmetric part of moments of velocity increments and first verify the following (somewhat contested) results: the 4/5-ths law holds in an intermediate range of scales and that the second order exponent over the same range of scales is anomalous, departing from the self-similar value of 2/3 and approaching a constant of 0.72 at high Reynolds numbers. We compare with some typical theories the dependence of longitudinal exponents as well as their derivatives with respect to the moment order n, and estimate the most probable value of the Hölder exponent. We demonstrate that the transverse scaling exponents saturate for large n, and trace this trend to the presence of large localized jumps in the signal. The saturation value of about 2 at the highest Reynolds number suggests, when interpreted in the spirit of fractals, the presence of vortex sheets rather than more complex singularities. In general, the scaling concept in hydrodynamic turbulence appears to be more complex than even the multifractal description.

show abstract

Multiscale anisotropic fluctuations in sheared turbulence with multiple states

Cited by 21 publications

References 47 publications

Discontinuous transitions towards vortex condensates in buoyancy-driven rotating turbulence

Discontinuous transitions towards vortex condensates in buoyancy-driven rotating turbulence

Steep Cliffs and Saturated Exponents in Three-Dimensional Scalar Turbulence

Scaling exponents saturate in three-dimensional isotropic turbulence

Contact Info

Product

Resources

About