Browsing by Author "Vernescu, Bogdan"

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    Micro-geometry effects on the nonlinear effective yield strength response of magnetorheological fluids
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2020) Nika, Grigor; Vernescu, Bogdan
    We use the novel constitutive model in [15], derived using the homogenization method, to investigate the effect particle chain microstructures have on the properties of the magnetorheological fluid. The model allows to compute the constitutive coefficients for different geometries. Different geometrical realizations of chains can significantly change the magnetorheological effect of the suspension. Numerical simulations suggest that particle size is also important as the increase of the overall particle surface area can lead to a decrease of the overall magnetorheological effect while keeping the volume fraction constant.
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    Multiscale modeling of magnetorheological suspensions
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2019) Nika, Grigor; Vernescu, Bogdan
    We develop a multiscale approach to describe the behavior of a suspension of solid magnetizable particles in a viscous non-conducting fluid in the presence of an externally applied magnetic field. By upscaling the quasi-static Maxwell equations coupled with the Stokes' equations we are able to capture the magnetorheological effect. The model we obtain generalizes the one introduced by Neuringer & Rosensweig for quasistatic phenomena. We derive the macroscopic constitutive properties explicitly in terms of the solutions of local problems. The effective coefficients have a nonlinear dependence on the volume fraction when chain structures are present. The velocity profiles computed for some simple flows, exhibit an apparent yield stress and the flowprofile resembles a Bingham fluid flow.