Effect of Size Distribution on Turbulence Induced by Inertial Particles

The mechanisms of multiphase turbulence remain unclear, despite the efforts yielding light upon its singular nature. Multiphase flows defy the postulates of classic Richardson-Kolmogorov turbulence and exhibit peculiar features, the most well-known of which is the -3 spectral slope. Of particular interest are multiphase dispersed flows, where particles (the term ‘particle’ herein is used in a wide sense) disrupt the natural evolution of vortex shedding within the fluid matrix whereas the production of turbulent kinetic energy at the particles’ scale might be significant.

 

This work investigates the effect of particle size on the turbulence signature produced by a swarm of spherical inertial particles falling subjected to their own weight within an initially quiescent fluid. To this effect, Direct Numerical Simulations are performed using an in-house Finite-Differences Navier-Stokes solver. Monodispersed and polydispersed distributions of different characteristic sizes will be compared to determine the effect of size on the turbulent kinetic energy production and the energy transfer among scales. Special attention is paid to the comparison of the spectral energy distribution across the different scales, wake-to-wake interaction and the probability density functions of second-order statistics.