  We study the rheological behaviour of a dense bidispersed suspension varying
the relative size of the two dispersed phases. The main outcome of our analysis
is that an enhanced flowability (reduced relative viscosity) of the suspension
can be achieved by increasing the dispersion ratio of the phases. We explain
the observed result by showing that the presence of large particles increases
the packing efficiency of the suspension, leading to a reduction of the
contribution of the contacts on the overall viscosity of the suspension in the
shear-thickening regime, i.e. where the contacts are the dominating component.
