Anisotropic diffusion and shear instabilities
نویسنده
چکیده
We examine the role of anisotropic turbulence on the shear instabilities in a stratified flow. Such turbulence is expected to occur in the radiative interiors of stars, due to their differential rotation and their strong stratification, and the turbulent transport associated with it will be much stronger in the horizontal than in the vertical direction. It will thus weaken the restoring force which is caused by the gradient of mean molecular weight (μ). We find that the critical shear which is able to overcome the μ-gradient is substantially reduced by this anisotropic turbulence, and we derive an estimate for the resulting turbulent diffusivity in the vertical direction.
منابع مشابه
Enhancing rotational diffusion using oscillatory shear.
Taylor dispersion--shear-induced enhancement of translational diffusion--is an important phenomenon with applications ranging from pharmacology to geology. Through experiments and simulations, we show that rotational diffusion is also enhanced for anisotropic particles in oscillatory shear. This enhancement arises from variations in the particle's rotation (Jeffery orbit) and depends on the str...
متن کاملAnisotropic diffusion in mesh-free numerical magnetohydrodynamics
We extend recently developed mesh-free Lagrangian methods for numerical magnetohydrodynamics (MHD) to arbitrary anisotropic diffusion equations, including: passive scalar diffusion, Spitzer–Braginskii conduction and viscosity, cosmic ray diffusion/streaming, anisotropic radiation transport, non-ideal MHD (Ohmic resistivity, ambipolar diffusion, the Hall effect) and turbulent ‘eddy diffusion’. W...
متن کاملEffects of Degree of Consolidation and Anisotropic Consolidation Stresses on Shear Modulus and Damping Ratio of Cohesive Soils at Low Strain
During consolidation process of saturated cohesive soil the soil stiffness increases. Increase of the effective stress due to dissipation of excess pore pressure causes additional stiffness of soil mass. This phenomenon has a very important effect on the behavior of saturated cohesive soils during dynamic loading. In the current investigation the changes in maximum shear modulus. Gmax and dampi...
متن کاملOn the Linear Stability of Weakly-Ionized, Magnetized Planar Shear Flows
We investigate the effects of ambipolar diffusion and the Hall effect on the stability of weaklyionized, magnetized planar shear flows. Employing a local approach similar to the shearingsheet approximation, we solve for the evolution of linear perturbations in both streamwisesymmetric and non-streamwise-symmetric geometries using WKB techniques and/or numerical methods. We find that instability...
متن کاملImage Denoising Using Anisotropic Diffusion Equations on Reflection and illumination Components of Image
This paper proposes a new hybrid method based on Homomorphic filtering and anisotropicdiffusion equations for image denoising. In this method, the Homomorphic filtering extracts the reflectionand illumination components of a noisy image. Then a suitable image denoising method based onanisotropic diffusion is applied to each components with its special user-defined parameters .This hybridscheme ...
متن کامل