Rheology is a term used to describe flow of fluids. The term is from Greek rheo (to flow) and logos (science). Therefore, it can also be defined as the science that describes flow of fluids. Liquid water is a simple fluid that flows readily when subjected to some force. For example, water flows out of a pipette at some velocity due to the effect of gravity (acting force). The following terms are used to describe flow of fluids:
- Viscosity: resistance to flow.
- Rate of shear: differential velocity between fluid layers.
- Shearing force: force parallel to the surface.
- Shearing stress: force per unit area of the fluid.
Rheology is important in many areas including the following:
- Pharmaceutical and cosmetic production of semi-solid products (creams, lotions, pastes, gels, and ointments). It is considered in choosing proper processing procedures and equipment ( such as mixers and filling machines), proper containers for packaging , and is also considered in studying product stability.
- Manufacturing of paints, diary products, and dough.
Note: solid systems can be viewed as fluids during deformation and their flow can be described with rheologic terms.
- Viscosity: resistance to flow.
- Rate of shear: differential velocity between fluid layers.
- Shearing force: force parallel to the surface.
- Shearing stress: force per unit area of the fluid.
Rheology is important in many areas including the following:
- Pharmaceutical and cosmetic production of semi-solid products (creams, lotions, pastes, gels, and ointments). It is considered in choosing proper processing procedures and equipment ( such as mixers and filling machines), proper containers for packaging , and is also considered in studying product stability.
- Manufacturing of paints, diary products, and dough.
Note: solid systems can be viewed as fluids during deformation and their flow can be described with rheologic terms.
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