![]() ![]() The word viscous comes from the Latin root viscum, meaning sticky. If the lava is thin (low viscosity), then it just flows out like water. This is because the lava has a hard time getting out and may burst out when it can. When the lava comes out very thickly ( viscous), there is more chance that it will erupt violently. Viscosity is used as a way to predict when volcanoes erupt. There are two types of viscosity: dynamic viscosity, measured in pascal seconds, and kinematic viscosity, measured in metres per second squared. Syrup would reach the bottom very slowly, and water would be much quicker. A way to test for viscosity is the speed at which the substance runs down a slope. Syrup and tar, on the other hand, have a high viscosity, as they are "thick". In a simple example, water has a low viscosity, as it is "thin". Viscosity is a physical property of fluids. “Correlation between in-line measurements of tomato ketchup shear viscosity and extensional viscosity.” Journal of Food Engineering 173 (2016): 8-14.Illustration of viscosity the violet fluid at the bottom has a higher viscosity than the clear one above Berta, Marco, Johan Wiklund, Reinhardt Kotzé, and Mats Stading.“Re: Viscosity” Received by Katie Jones, 2 Jan. ![]() “What Is Viscosity.” Brookfield Ametek, Accessed 12 Jan.“Non-Newtonian Flows.” Department of Chemical and Biomolecular Engineering, Clarkson University.(2002). The obvious advantage is the improved quality in batter consistency and potential cost savings in not reworking out of spec batches.” 4 References “Consequently, some major bakeries have progressed from making benchtop measurements with a rotational viscometer in the QC lab to using an on-line process viscometer which measures continuously as the batter is mixed and processed. There may also be a correlation between the density of the baked product and the viscosity of the batter. Thicker formulations are more difficult to move and handle in general. Processing the batter effectively in a production operation relates back to the viscosity issue. 5 For example, “the ability to characterize the pseudoplastic behavior of the batter can pay dividends in more ways than one. Understanding viscosity can allow you to determine the best process and equipment needed for commercial production of your product. 5 How Can Viscosity Impact Commercial Production 1 Small variations of processing conditions and raw materials can affect flow behavior and final viscosity. It is important to remember a material’s viscosity is not a single point measurement, but often depends on a number of factors, like time and temperature. Another option is an inline system allowing constant monitoring during production. Samples may be gathered during processing and lab tested by QA staff. Viscosity is measured with Viscometers, Rheometers, or Plastometers. 1 Cream to whipped cream is an example of a rheopectic food. Rheopexy: a material’s viscosity increases when sheared at a constant rate over time.1 Yogurt, pea protein and water, and honey are examples of thixotropic foods. Thixotropy: a material’s viscosity decreases when sheared at a constant rate over time.Its yield value will often make it refuse to pour from the bottle until the bottle is shaken or struck, allowing the catsup to gush freely. Tomato catsup is a good example of this type fluid. Once force is applied the material will flow. Plastic: a material appears to be solid until force is applied.3 Corn starch mixed with water and candy compounds are examples of dilatant foods. 1 Dal punto di vista microscopico la viscosità è legata all. Nellambito dei fenomeni di trasporto, la viscosità è il coefficiente di scambio di quantità di moto. This type of behavior is sometimes called shear-thickening. Confronto tra il comportamento di due sostanze aventi differente viscosità (in alto: sostanza a viscosità minore in basso: sostanza a viscosità maggiore). Dilatant: a material’s viscosity increases as the shear rate increases.1 Cake batter, agar-agar and fruit juice concentrates are examples of psuedoplastic foods. This type of flow behavior is sometimes called shear-thinning. Psuedoplastic: a material’s viscosity decreases as the shear rate increases.2 Non-Newtonian fluids can be categorized into five types based on the way a fluid’s viscosity changes in response to variations in shear rate. 2 Examples of non-Newtonian fluids are slurries, pastes and high molecular weight liquids. 2 Examples of Newtonian fluids are water, air, and ethanol.Ī non-Newtonian fluid is any fluid that does not obey the Newtonian relationship between the shear stress and shear rate. This means that a plot of shear stress versus shear rate at a given temperature is a straight line with a constant slope that is independent of the shear rate. Newtonian fluids do not change viscosity with shear. ![]()
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