Читать книгу The Rheology Handbook - Thomas Mezger - Страница 43

Figure 2.9 illustrates seven different types of laminar flow which may occur in a shear gap: (1) state-at-rest; (2) homogeneous laminar flow, showing a constant shear rate (see also Chapter 2.2); (3) wall-slip , the sample displays very pronounced cohesion while slipping along the walls without adhesion; (4) “plastic behavior” , only a part of the sample is sheared homogeneously (see also Chapter 3.3.4.2c); (5) transient behavior, showing a start-up effect as time-dependent transition until a steady-state viscosity value is reached (occurring above all at low shear rates; see also Chapter 3.3.1b); (6) shear-banding, exhibiting here pronounced cohesion of the medium band (see also Chapter 9.2.2); (7) shear-banding, showing here three different flow velocities or viscosities, respectively (see also here Chapter 9.2.2)

Figure 2.9: Different appearances of laminar flow in a shear gap, illustrated by use of the Two-Plates model