Solver reports that my "network is clustered" and cannot solve because my matrix is "ill-conditioned"

[jgostick]

If you have extracted your pore network from an image, and not removed blind pores from the image beforehand, you might end up with pores that are not connected to the main network. This can also happen if you are deleting pores from a generated network and get a bit carried away.

The solution to this problem, assuming you don't want to re-extract the network from an image with blind pores removed, is to trim the isolated pores from the network in OpenPNM. This example explains how to do this, and also explains why the solver fails.