Inertial range structure of turbulent velocity and scalar fields in a Lagrangian renormalized approximation

1986 ◽  
Vol 29 (3) ◽  
pp. 701 ◽  
Author(s):  
Yukio Kaneda
Keyword(s):  
Scalar Fields ◽  
Inertial Range ◽  
Turbulent Velocity

A scalar subgrid model with flow structure for large-eddy simulations of scalar variances

2000 ◽  
Vol 407 ◽  
pp. 315-349 ◽  
Author(s):  
P. FLOHR ◽  
J. C. VASSILICOS
Keyword(s):  
Flow Structure ◽  
Kinematic Model ◽  
Scalar Fields ◽  
Passive Scalar ◽  
Inertial Range ◽  
Large Eddy Simulations ◽  
Tracer Particles ◽  
Particle Pairs ◽  
Large Eddy ◽  
Scalar Variance

A new model to simulate passive scalar fields in large-eddy simulations of turbulence is presented. The scalar field is described by clouds of tracer particles and the subgrid contribution of the tracer displacement is modelled by a kinematic model which obeys Kolmogorov's inertial-range scaling, is incompressible and incorporates turbulent-like flow structure of the turbulent small scales. This makes it possible to study the scalar variance field with inertial-range effects explicitly resolved by the kinematic subgrid field while the LES determines the value of the Lagrangian integral time scale TL. In this way, the modelling approach does not rely on unknown Lagrangian input parameters which determine the absolute value of the scalar variance.The mean separation of particle pairs displays a well-defined Richardson scaling in the inertial range, and we find that the Richardson constant GΔ ≈ 0.07 which is small compared to the value obtained from stochastic models with the same TL. The probability density function of the separation of particle pairs is found to be highly non-Gaussian in the inertial range of times and for long times becomes Gaussian. We compute the scalar variance field for an instantaneous line source and find good agreement with experimental data.

scholarly journals New AdS4 vacua in dyonic ISO(7) gauged supergravity

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Nikolay Bobev ◽  
Thomas Fischbacher ◽  
Fridrik Freyr Gautason ◽  
Krzysztof Pilch
Keyword(s):  
Scalar Fields ◽  
Global Symmetry ◽  
Supergravity Theory

Abstract We identify 219 AdS4 solutions in four-dimensional dyonically gauged ISO(7) $$ \mathcal{N} $$ N = 8 supergravity and present some of their properties. One of the new solutions preserves $$ \mathcal{N} $$ N = 1 supersymmetry and provides a rare explicit example of an AdS4 vacuum dual to a 3d SCFT with no continuous global symmetry. There are also two new non-supersymmetric solutions for which all 70 scalar fields in the supergravity theory have masses above the BF bound. All of these AdS4 solutions can be uplifted to massive type IIA supergravity. Motivated by this we present the low lying operator spectra of the dual 3d CFTs for all known supersymmetric AdS4 solutions in the theory and organize them into superconformal multiplets.

scholarly journals Symmetry and unification from soft theorems and unitarity

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Clifford Cheung ◽  
Zander Moss
Keyword(s):  
Symmetry Algebra ◽  
Scalar Fields ◽  
Particle Interactions ◽  
Massive Scalar ◽  
Coset Space ◽  
Dimensional Theory ◽  
Finite Spectrum ◽  
Physical Constraints ◽  
High Energies ◽  
Zero Condition

Abstract We argue that symmetry and unification can emerge as byproducts of certain physical constraints on dynamical scattering. To accomplish this we parameterize a general Lorentz invariant, four-dimensional theory of massless and massive scalar fields coupled via arbitrary local interactions. Assuming perturbative unitarity and an Adler zero condition, we prove that any finite spectrum of massless and massive modes will necessarily unify at high energies into multiplets of a linearized symmetry. Certain generators of the symmetry algebra can be derived explicitly in terms of the spectrum and three-particle interactions. Furthermore, our assumptions imply that the coset space is symmetric.

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