Viscoplastic Media. The Shvedov-Bingham Fluid

Viscoplastic media. General formulas. For viscoplastic media, the shear rate in general depends on the stress as follows  

To obtain the explicit form of the function /(r) for the rheological models in question (see Table 6.3), one must express the shear rate 7 = dV/dt via r. 

The motion of plastic fluids with finite yield stress to has some qualitative specific features not possessed by nonlinearly viscous fluids. Let us consider a layer of a viscoplastic fluid on an inclined plane whose slope is gradually varied. It follows from (6.2.5) that, irrespective of the rheological properties of the medium, the tangential stress decreases across the film from its maximum value Tjnax = pgh sin a on the solid wall to zero on the free surface. Therefore, a flow in a film of a viscoplastic fluid can be initiated only when the tangential stress on the wall becomes equal to or larger than the yield stress to  

The maximum angle of inclination for which the stagnant film is still held on the plane is 

Basic parameters of film flow of non-Newtonian fluids along an inclined plane (m - pg sin a) 

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