1.2 Pseudo plastic and Dilatant Physiognomies
Pseudo plasticity is a phenomenon displayed by drilling mud systems
where the viscosity of the fluid decreases with an increase in shear
rate. This is also known as shear thinning. The reverse case of the
viscosity of the fluid increasing with an increase in the shear rate is
termed dilatant also known as shear thickening. It is affected by
properties such as particle size, shape and dissemination all of which
are controlled by the Hamaker theory and Van der Waals forces.