  Non-particulate continuum descriptions allow for computationally efficient
modeling of suspension flows at scales that are inaccessible to more detailed
particulate approaches. It is well known that the presence of particles
influences the effective viscosity of a suspension and that this effect has
thus to be accounted for in macroscopic continuum models. The present paper
aims at developing a non-particulate model that reproduces not only the
rheology but also the cell-induced velocity fluctuations, responsible for
enhanced diffusivity. The results are obtained from a coarse-grained blood
model based on the lattice Boltzmann method. The benchmark system comprises a
flow between two parallel plates with one of them featuring a smooth obstacle
imitating a stenosis. Appropriate boundary conditions are developed for the
particulate model to generate equilibrated cell configurations mimicking an
infinite channel in front of the stenosis. The averaged flow field in the bulk
of the channel can be described well by a non-particulate simulation with a
matched viscosity. We show that our proposed phenomenological model is capable
to reproduce many features of the velocity fluctuations.
