LAUSR

We performed direct numerical simulations of decaying isotropic turbulence laden with finite-size particles using an immersed boundary method combined with a soft-sphere collision model. The particle diameter is about 25 times the Kolmogorov length scale, and the particle-to-fluid density ratio ranges from 10 to 1000. The turbulence is enhanced by heavy particles but suppressed by light particles. The radial and spectral distributions of the main quantities are examined. The enstrophy budget is analyzed to reveal how the particles enhance the dissipation rate. The dependence of the two-way coupling term on the particle Reynolds number is loosely predicted. The relation between the particle-induced dissipation rate and particle Reynolds number is also estimated. The results indicate that the work done by particles outweighs the particle-induced dissipation at high particle Reynolds number, thereby enhancing the turbulence. Thus the particle Reynolds number should be a key parameter for turbulence modulatio...