Rheologica Acta, Vol.37, No.1, 68-72, 1998
Exact solution for compressive flow of viscoplastic fluids under perfect slip wall boundary conditions
Based on the perfect slip condition between rigid walls and fluids, the compressive flow of Herschel-Bulkley fluids and biviscous fluids was studied. The explicit expressions of stresses and fluid velocity were given. To move the rigid walls for a Herschel-Bulkley fluid with the yield stress (tau(0)), the mean pressure applied onto the rigid wall should be larger than 2 tau(0)/root 3. No yield surface exists in the interior of the fluids when flow occurs. For a biviscous fluid, a critical load was given. The fluid behaves like the Bingham fluid when the external applied load onto the wall is larger than the critical load, otherwise the fluid is Newtonian.