  Models for prediction of drag forces within a particle cloud following
shock-acceleration are evaluated with the aid of results from particle-resolved
simulations in order to quantify how much the disturbances introduced by the
proximity of nearby particles affect the drag forces. The drag models evaluated
here consist of quasi-steady forces, undisturbed flow forces, inviscid unsteady
forces, and viscous unsteady forces. Two dense particle curtain correction
schemes to these forces, based on volume fraction and input velocity, are also
evaluated. The models are tested in two ways; first they are evaluated based on
volume-averaged flow fields from particle-resolved simulations; secondly, they
are applied in Eulerian-Lagrangian simulations, and the results are compared to
the particle-resolved simulations.
  The results show that both correction schemes significantly improve the
particle force predictions, but the average total impulse on the particles is
still underpredicted by both correction schemes in both tests. With the volume
averaged flow fields as input, the volume fraction correction gives the best
results. However, in the Eulerian-Lagrangian simulations it is demonstrated
that the velocity fluctuation model, associated with the velocity correction
scheme, is crucial for obtaining accurate predictions of the mean flow fields.
