9/25/2023 0 Comments Newtonian fluidthe molecular size and architecture of polymers in solution or the particle size distribution in a solid suspension. It is also concerned with predicting mechanical behavior (on the continuum mechanical scale) based on the micro- or nanostructure of the material, e.g. In practice, rheology is principally concerned with extending continuum mechanics to characterize the flow of materials that exhibit a combination of elastic, viscous and plastic behavior by properly combining elasticity and ( Newtonian) fluid mechanics. Theoretical aspects of rheology are the relation of the flow/deformation behaviour of material and its internal structure (e.g., the orientation and elongation of polymer molecules), and the flow/deformation behaviour of materials that cannot be described by classical fluid mechanics or elasticity. The experimental characterisation of a material's rheological behaviour is known as rheometry, although the term rheology is frequently used synonymously with rheometry, particularly by experimentalists. Since Sir Isaac Newton originated the concept of viscosity, the study of liquids with strain-rate-dependent viscosity is also often called Non-Newtonian fluid mechanics. Some other non-Newtonian materials show the opposite behavior, rheopecty: viscosity increasing with relative deformation, and are called shear-thickening or dilatant materials. Ketchup is a shear-thinning material, like yogurt and emulsion paint (US terminology latex paint or acrylic paint), exhibiting thixotropy, where an increase in relative flow velocity will cause a reduction in viscosity, for example, by stirring. For example, ketchup can have its viscosity reduced by shaking (or other forms of mechanical agitation, where the relative movement of different layers in the material actually causes the reduction in viscosity) but water cannot. Rheology generally accounts for the behavior of non-Newtonian fluids by characterizing the minimum number of functions that are needed to relate stresses with rate of change of strain or strain rates. The large class of fluids whose viscosity changes with the strain rate (the relative flow velocity) are called non-Newtonian fluids. Only a small group of fluids exhibit such constant viscosity. Although this viscosity will change with temperature, it does not change with the strain rate. Newtonian fluids can be characterized by a single coefficient of viscosity for a specific temperature. It applies to substances that have a complex microstructure, 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, and to other materials that belong to the class of soft matter such as food. The term was inspired by the aphorism of Heraclitus (often mistakenly attributed to Simplicius), panta rhei ( πάντα ῥεῖ, 'everything flows' ) and was first used to describe the flow of liquids and the deformation of solids. Bingham, a professor at Lafayette College, in 1920, from a suggestion by a colleague, Markus Reiner. The term rheology was coined by Eugene C. Rheology is a branch of physics, and it is the science that deals with the deformation and flow of materials, both solids and liquids. Rheology ( / r iː ˈ ɒ l ə dʒ i/ from Greek ῥέω (rhéō) 'flow', and -λoγία (-logia) 'study of') is the study of the flow of matter, primarily in a fluid ( liquid or gas) 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. JSTOR ( May 2023) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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