Jamming and Rheology of Fluidized Beds of Magnetized Particles

• Published in: Applied rheology (Lappersdorf, Germany) Vol. 21; no. 3
• Main Authors: Valverde J.M., Espin M.J., Quintanilla M.A.S.
• Format: Journal Article
• Language: English
• Published: De Gruyter 01.06.2011
• Subjects: carreau model; composites; cox-merz rule; magnetic particles; viscosity
• ISSN: 1617-8106
• DOI: 10.3933/applrheol-21-35179

The interaction between magnetic particles in a bed fluidized by a gas is determined by the magnetizing action of an externally applied magnetic field. As the strength of the field is increased there comes a point at which the bed transits from a fluidlike to a solidlike stable state. Interparticle attractive forces induced by the applied field causes chainlike agglomeration of the particles, which confers the stabilized structure with a mechanical strength. In this paper we report experimental results on the yield stress of fluidized beds of fine magnetic particles stabilized by an externally applied magnetic field. Our results show that, in analogy with magnetorheological fluids (MRFs), particle structuring determines essentially the yield stress of magnetofluidized beds (MFBs). Moreover, our work shows that the dependence of the yield stress on particle size, which stands as a controversial issue in the study of MRFs, can be understood from the analysis of the jamming transition as affected by the size of the particles and the strength of the field.