Rheology is the study of flow. Here in Hawaii, lava is flowing into the sea. Geologists and geophysicists study such states of molten rock. It is also the flow of ketchup, mustard, honey, foams, paints and/or any substance that differs from a full liquid or solid state.
Rheo, from the Greek word for “flow,” plus “ology,” which always denotes the “study of,” is the basis for the term in science and industry that investigate rheology.
Such sluggish fluids are said to be non-Newtonian. Their viscosity, or thickness, allows that they do not spill or have the same reactions to gravity that liquid water has when poured from a bottle, for example. Anyone who has ever played with their pudding, or the kind of corn starch play dough many have made at home, can be considered an amateur rheologist.
In fact, many, many “fluids” are non-Newtonian. Even water, when frozen or slushy, as atop a glacier, or when foaming on a shore, is behaving with properties of rheology and deformation, which can be measured, studied, deciphered and predicted.
There are many fields, then, that use rheology. The oil drilling companies have an interest in the efficiency of flow, for extraction, as do many other industries, such as food manufacturers. The term deformation is also used to describe the unique way, for example, that a face cream or other product will “deform,” or have an impression upon it, that another fluid may not. Mustard or mayonnaise may stay high upon the sides of a jar, but a thinner fluid like syrup will not deform, but ooze back into a level and even surface.
And many people, even if they have never heard the term, have experimented with peanut butter, sand boxes, clay, foam and so much more. The unique properties, the “behavior,” of slower moving substances are intriguing. All human children, of course, are naturally drawn to anything goopy, mush-like, foamy or even muddy.
There is even an international Society of Rheology. It is called the Society of Rheology, or SOR. Begun in 1929, the group has been internationally holding conferences and conventions all around the world. Their logo is an hourglass. The flow of sand through the hourglass shows just one example of rheological properties, in this case, of sand.
Physicists, researchers, corporate scientists and engineers are among the many peer-reviewed members who may share a child-like enthusiasm for playing with slime.
