Rheology

Rheology is the study of the deformation and flow of matter. The term rheology was coined by Eugene Bingham, a professor at Lehigh University, in 1920, from a suggestion by Markus Reiner, inspired by the Heraclitus' famous expression "panta rhei": everything flows.

Basic rheological terms are:

• Viscosity
• Shear Rate and Elongation Rate
• Shear Stress
• Newtonian Law

Fluids can be categorized in

• newtonian fluids (the fluid viscosity is constant) and
• non-newtonian fluids (the fluid viscosity depends on the stresses acting on the fluid) which can by subclassified into
  • generalized non-newtonian fluids (also called purely viscous fluids) and
  • viscoelastic fluids.

Rheological properties are determined by means of rheometry.