Influence of molecular diffusion on alignment of vector fields: Eulerian analysis

Gonzalez, M.

doi:10.1007/s00162-016-0417-6

Cited by 1 publication

(6 citation statements)

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“…Brandenburg et al [22] addressed the influence of the magnetic diffusivity on the alignment of flux lines of the magnetic field. Recently, a Eulerian numerical study [23] confirmed the basic analysis of Constantin et al [18] regarding the alignment and structure of a diffusive vector field.…”

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confidence: 60%

“…The former, D∆G and D∆θ, express diffusive smoothing; the latter, −D|∇θ| 2 G = D nl (G) and 2D(∇G.∇θ)/G = D nl (θ), express dissipation caused by angle gradients, and diffusive tilting resulting from the interaction between norm gradient and orientation gradient. Detailed analyses of these terms were made in previous studies [18,23].…”

Section: Equations For the Gradient Of A Scalarmentioning

confidence: 99%

“…As was done in a previous, Eulerian study [23], the flow is specialized to a twocomponent velocity field, namely (u, v, w) = (∂ψ/∂y, −∂ψ/∂x, 0), with the general form of the streamfunction, ψ, given by:…”

Section: Model Flowmentioning

confidence: 99%

“…By simply changing the value of a flow parameter, different regimes are considered as regards the degree of adiabaticity of scalar gradient dynamics. In this respect, the analysis is more general than the previous, Eulerian one [23].…”

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confidence: 96%

“…The analysis is specifically focused on the way in which the inviscid alignment and dynamics of scalar gradient orientation are altered as the Péclet number is decreased. The analytic, two-dimensional, model flowfield was already shown to include the essential features of flow structure for investigating the kinematics of transported vectors [23]. By simply changing the value of a flow parameter, different regimes are considered as regards the degree of adiabaticity of scalar gradient dynamics.…”

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confidence: 99%

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Alignment dynamics of diffusive scalar gradient in a two-dimensional model flow

Gonzalez

2018

Theor. Comput. Fluid Dyn.

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The Lagrangian two-dimensional approach of scalar gradient kinematics is revisited accounting for molecular diffusion. Numerical simulations are performed in an analytic, parameterized model flow, which enables considering different regimes of scalar gradient dynamics. Attention is especially focused on the influence of molecular diffusion on Lagrangian statistical orientations and on the dynamics of scalar gradient alignment.A number of basic and practical questions in fluid dynamics are connected to the transport of vectors [1, 2], an issue therefore relevant to many fields -process engineering, reacting flows, mixing, astrophysical flows, etc. Vectors defining material lines or surfaces, vorticity, the vorticity gradient in two-dimensional flows, gradients of scalar quantities such as concentration or temperature, the magnetic field vector in magnetohydrodynamics, are transported vectors.Most often, analyses are with regard the growth -or decay -of the magnitude of the transported vector. The growth of the scalar gradient, for example, indicates the production of small scales in the scalar field; addressing the dynamo effect needs to determine the physical conditions in which the magnetic field vector is amplified. The bare kinematics of vector amplification -in non-diffusive tracer advection, kinematic dynamo, or inviscid vortex stretching -is a matter of strain level and orientation within the strain eigenframe. Just like strain intensity, vector orientation is essential to the process and was investigated in many studies [3][4][5][6][7] (see [2] for more references).

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confidence: 60%

Section: Equations For the Gradient Of A Scalarmentioning

confidence: 99%

Section: Model Flowmentioning

confidence: 99%

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confidence: 96%

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confidence: 99%

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