  We study, by computer simulations, the role of different dissipation forces
on the rheological properties of highly-dense particle-laden flows. In
particular, we are interested in the close-packing limit (jamming) and the
question if "universal" observables can be identified that do not depend on the
details of the dissipation model. To this end, we define a simplified
lubrication force and systematically vary the range $h_c$ of this interaction.
For fixed $h_c$ a cross-over is seen from a Newtonian flow regime at small
strain rates to inertia-dominated flow at larger strain rates. The same
cross-over is observed as a function of the lubrication range $h_c$. At the
same time, but only at high densities close to jamming, particle velocity as
well as local density distributions are unaffected by changes in the
lubrication range -- they are candidates for "universal" behavior. At densities
away from jamming, this universality is lost: short-range lubrication forces
lead to pronounced particle clustering, while longer-ranged lubrication does
not. These findings highlight the importance of "geometric" packing constraints
for particle motion -- independent of the specific dissipation model. With the
free volume vanishing at random-close packing, particle motion is more and more
constrained by the ever smaller amount of free space. On the other side,
macroscopic rheological observables, as well as higher-order correlation
functions retain the variability of the underlying dissipation model.
