Eur. Phys. J. Special Topics 143, 181-189 (2007)
https://doi.org/10.1140/epjst/e2007-00086-x

Particles in fluids

¹ IfB, ETH Zürich, Hönggerberg, 8093 Zürich, Switzerland
² Departamento de Física, Universidade Federal do Ceará, 60451-970 Fortaleza Ceará, Brazil

Abstract

For finite Reynolds numbers the interaction of moving fluids with particles is still only understood phenomenologically. We will present three different numerical studies all using the solver “Fluent” which elucidate this issue from different points of view. On one hand we will consider the case of fixed particles, i.e. a porous medium and present the distribution of channel openings and fluxes. These distributions show a scaling law in the density of particles and for the fluxes follow an unexpected stretched exponential behaviour. The next issue will be filtering, i.e. the release of massive tracer particles within this fluid. Interestingly a critical Stokes number below which no particles are captured and which is characterized by a critical exponent of 1/2. Finally we will also show data on saltation, i.e. the motion of particles on a surface which dragged by the fluid performs jumps. This is the classical aeolian transport mechanism responsible for dune formation. The empirical relations between flux and wind velocity are reproduced.