Geometry effects in squeeze flow of Bingham plastics

Squeeze flow of Bingham plastics shows small unyielded regions confined only near the center of the disks. Previous simulation results on axisymmetric coaxial disks are extended to aspect ratios ranging from 0.01 to 1, and to planar parallel plates of infinite width. New results are given for a wide range of Bingham numbers using the continuous modification of Papanastasiou for the Bingham model. Axisymmetric geometries give smaller unyielded regions than planar ones, while big aspect ratios give larger unyielded regions than small ones for the same Bingham number. Calculations of the squeeze force along disks or plates for different aspect ratios are also given and fitted to easy-to-use equations. (C) 2002 Elsevier Science B.V. All rights reserved.