Variance of the velocity in suspensions of particles does not diverge

Previous theoretical work predicted that the variance of the velocity in a suspension of spherical particles should diverge with system size, but experiments find the variance asymptotes to a finite value at large system size. Accounting for the inertia of the suspending fluid is shown to resolve this discrepancy and provides predictions for how the variance depends on the volume fraction and densities of the suspended particles and the densities of the fluid.