This allows for the most reproducible results, and adequately captures the exact method used to measure this viscosity. In general, it is good practice to report the measured viscosity, the instrument that was used, the spindle, speed, and temperature. When reporting a viscosity measured using our instruments, it is important to include the appropriate information that may be relevant to your situation. Whatever option you choose, it is important to note the temperature of the fluid along with the viscosity you’ve measured. You can either measure and report the current temperature of the fluid during the test, or you can actively control the temperature of the fluid during the test. There are two ways to deal with temperature in your viscosity measurements.
This is similar to non-Newtonian fluids, where some fluids are affected much more or less than others. Some fluids change viscosity based on the forces applied to them, but all fluids change in viscosity to some degree when the temperature of the fluid changes.
Many of our spindles and measurement systems have known shear rate constants associated with them, which allow you to compare measurements of non-Newtonian fluids and characterize their behavior across a range of shear rates. When in doubt, it is always safer to assume your sample is non-Newtonian. Some common examples of non-Newtonian fluids includes mayonnaise, soaps, slurries, and many more. There are many more complicated behaviors, but that is beyond the scope of this article.
The two most common behaviors exhibited by non-Newtonian fluids are shear-thinning, where the substance will decrease in viscosity as the shear forces on it increase, or shear-thickening where the viscosity increases as the shear forces on the fluid increase. Fluids can be very mildly non-Newtonian and barely change viscosity over a huge range of forces, or they can be severely non-Newtonian and change from free-flowing fluids to almost solid masses when mild forces are applied. Non-Newtonian fluids - Their apparent viscosity changes depending on the amount of shear applied, or how roughly or gently they are disturbed.
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