Spreading of Non-Newtonian Liquids over Solid Substrates

5 SPREADING OF NON-NEWTONIAN LIQUIDS OVER SOLID SUBSTRATES 

The theoretically predicted spreading laws for gravitational and capillary regimes have been deduced as R(t) and R(t) respectively, where R(t) is the radius of the base of the spreading drop, and t is the time. Comparison of the predicted spreading laws with experimental data in Chapter 3 has shown excellent agreement. 

However, a number of liquids (polymer liquids and suspensions [18,19]) show a non-Newtonian behavior. The aim of this section is to extend the similarity solution method used in Chapter 3 to the case of spreading of non-Newtonian liquids (Ostwald-de Waele liquids) over solid surfaces and to deduce the corresponding spreading laws for both gravitational and capillary regimes of spreading. 

Governing Equation for the Evolution of the Profile OF THE Spreading Drop 

The rheological properties of the liquid are determined by the viscosity dependency, ti(5), on the shear deformation rate, S [18]. 

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