Micheline Abbas, LGC (Toulouse)
30 janvier 2015
The migration of particles/droplets across the streamlines of a pipe flow leads to non-uniform distribution of the dispersed phase, which might impact considerably the properties of the suspension flow. In the case of rigid spherical and neutrally buoyant particles, this phenomenon depends exclusively on the flow inertia, particle-to-pipe size ratio and volume fraction (concentration) of the dispersed phase. Local simulations and experiments were used in order to study the migration of particles in confined flows.
I will discuss two situations where the driving mechanisms of the particle migration are different. In the case where the particle Reynolds number is finite, the isolated particles migrate towards the pipe/channel wall due to their inertial interaction with the non-linear velocity profile at the particle scale. Collective effects take place when the concentration increases. In another case where the particle Reynolds number is negligible, the particles migrate towards the pipe center only at very high concentration. The relation between the shear-induced migration and the shear-thinning like behavior of a concentrated emulsion flow will be discussed.
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