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1 Time-dependent shear stress: τ(t), see Figure 3.35

2 Time-dependent shear rate: γ ̇ (t), see Figure 3.36

Further results: Time-dependent viscosity η(t), see Figure 3.37

The shapes of the curves of τ(t) and η(t) are similar because τ and η are proportional since τ = η ⋅ γ ̇ , here with γ ̇ = const. However, the curves of γ ̇ (t) and η(t) are inversely, because γ ̇ and η are inversely proportional since η = τ/ γ ̇ here with τ = const.

Figure 3.34: Preset of a constant shear rate

Figure 3.35: Time-dependent shear stress curves:

(1) with no change in viscosity with time

(e. g. viscosity reference fluids, standard oils)

(2) decreasing viscosity with time (e. g. emulsion paints, ketchups, yogurts)

(3) increase in viscosity with time (e. g. hardening process of adhesives, gel formation)

Figure 3.36: Time-dependent shear rate curves: for (1) to (3) see text of Figure 3.35

Figure 3.37: Time-dependent viscosity curves: for (1) to (3) see text of Figure 3.35