Identification of Bingham fluid flow parameters using a simple squeeze test

Squeeze flow of a Bingham fluid between two parallel plates is studied by means of a variational approach [K.J. Zwick, P.S. Ayyaswamy, I.M. Cohen, Variational analysis of the squeezing flow of a yield stress fluid, J. Non-Newtonian Fluid Mech., 63 (1996) 179–199.]. The trial velocity field consists of a central region of pure extensional flow, mid-way between the plates, and sheared regions adjacent to the plates. The width of the region of extensional flow is chosen to minimise an energy dissipation functional. The analysis assumes that the separation of the plates is small compared to the plate radius, and the predictions are compared with those of previously published analyses.