Turbulence modulation by finite-size particles of different diameters and particle-fluid density ratios in homogeneous isotropic turbulence

In this paper, the influence of particle-fluid density ratio and particle diameter on the turbulence modulation by finite-size particles in forced homogeneous isotropic turbulence is investigated. Results show that the presence of finite-size particles always attenuate the turbulence, and the attenuation is larger for particles with larger density when the particle diameter is fixed. But the attenuation is smaller for particles with larger diameter if the density is fixed, and the weaker attenuation is due to the wake fluctuation when the particle Reynolds number is large enough. The turbulence kinetic energy is attenuated at the large scales and augmented at the small scales. The radial dissipation profiles show that the region affected by the particles with same diameter is identical, but the dissipation near the particle surface is larger if the density is larger due to larger slip velocity and particle Reynolds number. For particles with same density, smaller particles have smaller dissipation near the particle surface but the influence region is larger, and the combined effect leads to the result that the contribution of dissipation in the influence region of smaller particles to the total dissipation is larger. The influence region mainly depends on the particle diameter.