EFFECTS OF PARTICLE SIZE AND SOLID-TO-FLUID DENSITY RATIO ON THE DYNAMICS OF PARTICLE-LADEN HOMOGENEOUS SHEAR TURBULENCE

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Particulate turbulent flows are encountered in many natural and industrial situations. In the present study, we numerically investigate how the dynamics of particle-laden homogeneous shear turbulence depends on the particle size and solid-to-fluid density ratio in order to deepen the understanding of the interaction between particles and turbulent shear flows. We consider the situation where the particle diameter is five to ten times larger than the Kolmogorov scale of turbulence with a solid-to-fluid density ratio between 0.5 and 10. An immersed boundary method is adopted to represent the spherical finite-size particle. Numerical results show that small particles enhance the viscous dissipation inside viscous layers surrounding particles, which leads to the suppression of the growth of homogeneous shear turbulence. The viscous dissipation is further enhanced through the modification of turbulence structure. The enhancement of the viscous dissipation depends strongly on the solid-to-fluid density ratio as well as particle size. In the cases of high density ratio, the generation of vortex tubes is activated around the particles, which leads to the modification of vortex layers and the enhancement of the viscous dissipation.