  We perform fully coupled numerical simulations using immersed boundary
methods of finite-size spheres and fibres suspended in a turbulent flow for a
range of Taylor Reynolds numbers $12.8<Re_\lambda<442$ and solid mass fractions
$0\leq M\leq1$. Both spheres and fibres reduce the turbulence intensity with
respect to the single-phase flow at all Reynolds numbers, with fibres causing a
more significant reduction than the spheres. The particles' effect on the
anomalous dissipation tends to vanish as $Re \to \infty$. A scale-by-scale
analysis shows that both particle shapes provide a "spectral shortcut" to the
flow, but the shortcut extends further into the dissipative range in the case
of fibres. Multifractal spectra of the near-particle dissipation show that
spheres enhance dissipation in two-dimensional sheets, and fibres enhance the
dissipation in structures with a dimension greater than one and less than two.
In addition, we show that spheres suppress vortical flow structures, whereas
fibres produce structures which completely overcome the turbulent vortex
stretching behaviour in their vicinity.
