Viscosity of Ideal Liquids

For simple shear flows, Eq. (4.134) becomes the familiar expression for Newtonian liquids. 

Owing to the fact that a viscous material still responds elastically to an isotropic pressure, Eq. (4.133a) should be written as 

For an incompressible fluid the rate of dilatation vanishes, and we obtain 

By taking into account the earlier relation, Hl = 3r, Eq. (4.144) can be written as 

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