532 research outputs found

    Electroviscous effects of simple electrolytes under shear

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    On the basis of a hydrodynamical model analogous to that in critical fluids, we investigate the influences of shear flow upon the electrostatic contribution to the viscosity of binary electrolyte solutions in the Debye-H\"{u}ckel approximation. Within the linear-response theory, we reproduce the classical limiting law that the excess viscosity is proportional to the square root of the concentration of the electrolyte. We also extend this result for finite shear. An analytic expression of the anisotropic structure factor of the charge density under shear is obtained, and its deformation at large shear rates is discussed. A non-Newtonian effect caused by deformations of the ionic atmosphere is also elucidated for τDγ˙>1\tau_D\dot{\gamma}>1. This finding concludes that the maximum shear stress that the ionic atmosphere can support is proportional to λD−3\lambda_D^{-3}, where γ˙\dot{\gamma}, λD\lambda_D and τD=λD2/D\tau_D=\lambda_D^2/D are, respectively, the shear rate, the Debye screening length and the Debye relaxation time with DD being the relative diffusivity at the infinite dilution limit of the electrolyte.Comment: 13pages, 2figure

    Kinetic formulation and global existence for the Hall-Magneto-hydrodynamics system

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    This paper deals with the derivation and analysis of the the Hall Magneto-Hydrodynamic equations. We first provide a derivation of this system from a two-fluids Euler-Maxwell system for electrons and ions, through a set of scaling limits. We also propose a kinetic formulation for the Hall-MHD equations which contains as fluid closure different variants of the Hall-MHD model. Then, we prove the existence of global weak solutions for the incompressible viscous resistive Hall-MHD model. We use the particular structure of the Hall term which has zero contribution to the energy identity. Finally, we discuss particular solutions in the form of axisymmetric purely swirling magnetic fields and propose some regularization of the Hall equation

    Experimental and Molecular Modeling Study of the Three-Phase Behavior of ( n

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