Simple shear in a magnetic suspension - Numerical simulation

• published: 06 Oct 2014
• views: 20

This video shows the influence of a simple shear in a magnetic suspension subjected to hydrodynamic and magnetic interactions. The simulations were done in a research code written by Gontijo (2013) during his PhD Thesis under the supervision of Prof. Francisco Ricardo Cunha. Both are members of the Vortex Group - Fluid Mechanics of Complex Flows, at the University of Brasília - Brazil. In these videos the volume fraction of particles is very low (diluted suspension ~ around 1%) and the intensity of inteparticle magnetic interaction is also low (lambda around 0.1). In both cases there is an application of a moderated external field (alpha = 5). In the left we have a clear tendency of particle aligment in the field direction. There is also a tendency of aggregate formation with anisotropic structures (long chains in the field direction). When we apply a simple shear we may observe two interesting phenomena: first we have an attempt of the fluid's vorticity (imposed by shear stresses) of misaligning the particles against the direction of the applied field. The second behavior is the attempt of the shear in breaking possible anisotropic chains. Both phenomena are related to rheological responses of this complex fluid. The extra effort of the shear in misaligning the particles from the field direction leads to an increase on the fluid's viscosity. The break up of long chains in the field direction leads to a shear thinning behavior of a magnetic fluid when subjected to the application of an external field. Both phenomena are documented in the Master Degree's Dissertation of Adriano P. Rosa (2014), done under the supervision of Prof. Francisco Ricardo Cunha. All the videos published in this channel were developed in scientific works of the Vortex Group - Fluid Mechanics of Complex Flows, at the University of Brasília - Brazil.