43,304 research outputs found

    Tipstreaming of a drop in simple shear flow in the presence of surfactant

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    We have developed a multi-phase SPH method to simulate arbitrary interfaces containing surface active agents (surfactants) that locally change the properties of the interface, such the surface tension coefficient. Our method incorporates the effects of surface diffusion, transport of surfactant from/to the bulk phase to/from the interface and diffusion in the bulk phase. Neglecting transport mechanisms, we use this method to study the impact of insoluble surfactants on drop deformation and breakup in simple shear flow and present the results in a fluid dynamics video.Comment: Two videos are included for the Gallery of Fluid Motion of the APS DFD Meeting 201

    Exchange Field-Mediated Magnetoresistance in the Correlated Insulator Phase of Be Films

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    We present a study of the proximity effect between a ferromagnet and a paramagnetic metal of varying disorder. Thin beryllium films are deposited onto a 5 nm-thick layer of the ferromagnetic insulator EuS. This bilayer arrangement induces an exchange field, HexH_{ex}, of a few tesla in low resistance Be films with sheet resistance RRQR\ll R_Q, where RQ=h/e2R_Q=h/e^2 is the quantum resistance. We show that HexH_{ex} survives in very high resistance films and, in fact, appears to be relatively insensitive to the Be disorder. We exploit this fact to produce a giant low-field magnetoresistance in the correlated insulator phase of Be films with RRQR\gg R_Q.Comment: To be published in Physical Review Letter
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