VORTEX - Grupo de Mecânica dos Fluidos de Escoamentos Complexos

Mecânica da sedimentação de partículas esféricas interagindo hidrodinamicamente (2005).

Autor: Gustavo Coelho Abade

Orientador: Francisco Ricardo Cunha

The general purpose of this work is to develop a fundamental study of gravity induced sedimentation of spherical particles immersed in a Newtonian fluid. It is assumed low particle Reynolds number conditions, being the suspension flow governed entirely by inter-particle hydrodynamic interactions with negligile effects of fluid inertia. The study is carried out by simulating numerically the suspension microstructure, being the motion of each particle described individually. It was developed numerical schemes aimed at reducing the large computational effort involved in simulations of many-body systems. From static simulations, estimates of the mean settling velocity as a func- tion of particle volume fraction were determined for mono and bidispersions. From dynamic simulations, the long time behaviour of mono and polidispersions, which is characteristic of a diffusion process, was characterized by self-dispersion coefficients. Based on a continuum model of sedimentation dynamics, this work also addresses the behaviour of large-scale velocity fluctuations in stratified gas-solid suspensions. A pre- liminary study of particle pressure in liquid-solid fluidized suspensions was conducted by considering the steady sedimentation geometry. It was simulated the sedimentation of particle blobs (spherical and toroidal) and the effects of polydispersity on the com- plex shape evolution of these clusters were investigated. Our simulations reproduce the dominant behaviour of sedimenting particles and the numerical code developed in this work permits future investigations of diverse phenomena occuring in suspensions flow.


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