Rheology

Rheology is the study of the flow of matter, primarily in a liquid state, but also as 'soft solids' or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force. It applies to substances which have a complex molecular structure, such as muds, sludges, suspensions, polymers and other glass formers (e.g., silicates), as well as many foods and additives, bodily fluids (e.g., blood) and other biological materials or other materials which belong to the class of soft matter.

History

The term rheology was coined by Eugene C. Bingham, a professor at Lafayette College, in 1920, from the Greek ῥέω (rheo, "flow") and -λoγία, -logia, "study of". The term was inspired by the aphorism of Heraclitus, "Panta rhei", everything flows.

Scope

Rheology has applications in materials science, geophysics, and biology. Materials with the characteristics of rheological fluids are found in many industries (food, cosmetics, polymers), and many natural phenomena (mudflows, landslides, lava flows, glaciers). Rheology has even been used to study the flow of traffic and the flight of insects.

Rheometers

The principal method of measuring rheology is the rheometer, an instrument which measures the response of a material flow or deformation to applied forces. It is used for those fluids which cannot be defined by a single value of viscosity and therefore require more parameters to be set and measured than is the case for a viscometer.

See also

• Viscosity
• Non-Newtonian fluid
• Yield stress
• Herschel-Bulkley fluid
• Bingham plastic
• Thixotropy
• Rheometry
• Rheoscope

Rheology

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  Cellulose strand
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  Sol-gel silicate bonds