Research

Finite-inertia effects in colloidal and non-colloidal systems

Principal investigator:

Flows containing solid particles underpin a huge variety of technologies, from microfluidics to fluidized beds. In the vast majority of simulations of particulate materials, forces and torques on the particles are either modelled ad-hoc, or treated neglecting non-linearities in the Navier-Stokes equation. Physalis, a numerical method that I co-developed during my PhD, is able to calculate hydrodynamic interaction between particles and their transport owing to fluid motion from first principles, i.e. by solving the full Navier-Stokes equation and enforcing the no-slip condition exactly. The figures below show a numerical study of the sedimentation of a semi-concentrated suspension at finite Reynolds number (Fig. 1) , and the interaction of finite-size particles with a stream of homogeneous-isotropic turbulence (Fig. 2).

Fig. 1 More than one thousands particles sedimenting in a periodic box. The average particle Reynolds number is 10, and the particle volume fraction is about 13%. Colours indicate kinetic energy values. Several particle clusters can be noticed. The fluid exhibit  turbulent-like fluctuations (pseudo-turbulence).

Fig. 2 Viscous dissipation field around a finite size particle exposed to a turbulent stream. Notice the high-dissipation level in the boundary layer.