Numerical study of the Bingham squeeze film problem

In studies of the flow of a Bingham fluid in a parallel-plate plastometer there has been disagreement about whether or not a yield surface exists, and if it does exist what shape the yield surface has. The present authors have re-exemined the problem using a finite element program and have concluded that a small plug of unyielded fluid exists adjacent to the centre of the plates. This result has been verified by replacing the unyielded plug with a solid body.