We are using the MatPIV Matlab toolkit: http://www.math.uio.no/~jks/matpiv/ [Broken] However, we are having trouble using the toolkit with viscoplastic media. It was expected to find a yielded region and a unyielded region, however, from the results of MatPIV it appeared that the whole area was flowing. This contradicts visual inspection of the system with tracers, in which flow was apparent only near moving inclusions. Is anyone familiar with MatPIV that might help us explain and possibly work around the problem? Thanks!