Inelastic accretion of inertial particles by a towed sphere

Robin Vallée (1, 2) , Christophe Henry (2) , Elie Hachem (1) , Jérémie Bec (2)

1 CEMEF - Centre de Mise en Forme des Matériaux
2 LAGRANGE - Joseph Louis LAGRANGE

The problem of accretion of small particles by a sphere embedded in a mean flow is studied in the case where the particles undergo inelastic collisions with the solid object. The collision efficiency, which gives the flux of particles experiencing at least one bounce on the sphere, is found to depend upon the sphere Reynolds number only through the value of the critical Stokes number below which no collision occurs. In the absence of molecular diffusion, it is demonstrated that multiple bounces do not provide enough energy dissipation for the particles to stick to the surface within a finite time. This excludes the possibility of any kind of inelastic collapse, so that determining an accretion efficiency requires modeling more precisely particle-surface microphysical interactions. A straightforward choice is to assume that the particles stick when their kinetic energy at impact is below a threshold. In this view, numerical simulations are performed to describe the statistics of impact velocities at various values of the Reynolds number. Successive bounces are shown to enhance accretion. These results are put together to provide a general qualitative picture on how the accretion efficiency depends upon the nondimensional parameters of the problem.

Domaines: Matériaux

Robin Vallée, Christophe Henry, Elie Hachem, Jérémie Bec. Inelastic accretion of inertial particles by a towed sphere. Physical Review Fluids, 2018, 3 (2), pp.Article 024303. ⟨10.1103/PhysRevFluids.3.024303⟩. ⟨hal-01737137⟩