China
Africa
Explore chapters and articles related to this topic
Fluid Flow
Published in C. Anandharamakrishnan, S. Padma Ishwarya, Essentials and Applications of Food Engineering, 2019
C. Anandharamakrishnan, S. Padma Ishwarya
On the other hand, fluids with shear-dependent viscosity are known as non-Newtonian fluids. For non-Newtonian fluids, the relationship between shear stress and shear rate is not linear (Figure 4.2). These are in turn classified as time dependent and time independent, as shown in Figure 4.3.
Testing and Analysis of Blended Lubricants
Published in R. David Whitby, Lubricant Blending and Quality Assurance, 2018
Non-Newtonian fluids exhibit a lower viscosity when subjected to high shear rates than Newtonian fluids having the same viscosity at low shear. Oils which contain viscosity index improving polymers exhibit non-Newtonian viscosity behaviour. This reduced viscosity at high shear rate may be temporary and reversible, depending on the stability to shear of the VI improving polymer. If, however, the shear rate is too high, the polymer molecules may be broken.
Introduction
Published in Steven G. Penoncello, Thermal Energy Systems, 2018
Fluids that behave according to Newton’s law of viscosity, Equation 1.47, are known as Newtonian fluids. Many industrial fluids are Newtonian such as water, light oils, gasoline, brines, and organic solvents. However, there are many other substances that do not obey Equation 1.47. These are known as non-Newtonian fluids. Examples of non-Newtonian fluids are suspensions, slurries, gels, colloids, and polymers. The study of non-Newtonian fluids is a complex subject within the broader science of rheology.
Entropy approach of hydromagnetic Williamson nanofluid flow with Joule heating
Published in International Journal of Ambient Energy, 2023
Amir Yaseen Khan, Ibukun S. Oyelakin, Sabyasachi Mondal, Sharadia Dey
Prandtl (1904) introduced understanding boundary layer flow in fluid dynamics and provided a way to greatly simplify the constitutive equations of flow around an obstruction. For an excellent treatment of this subject refer to Schlichting (1951). Newtonian or non-Newtonian fluids are distinguished based on their viscosity at different shear rates. The fluids with constant viscosity for any shear rate are called Newtonian fluids while those fluids whose viscosity varies with shearing rates are called non-Newtonian fluids. For an excellent coverage of rheological behaviour of the fluids one can refer to Morrison (2001). Williamson (1929) derived a mathematical model for describing a class of fluids that were neither like plastics nor like Newtonian fluids. He documented that the flow of these fluids was very similar to plastics and only differed from them in that they did not possess a real yield value. Thus he named them pseudoplastic fluids. Today these fluids are known as Williamson fluids. They are also called shear-thinning fluids because with higher shear rates their viscosity decreases.
Research on rheology performance and sealing effect of alkali-activated GGBS paste used for tunnel leakage plugging
Published in Journal of Sustainable Cement-Based Materials, 2023
Ping Li, Shiwei Liu, Yin Bai, Jianhui Tang, Jun Tao
Viscosity is a basic rheological parameter of fluids and reflects the resistance of a fluid to deformation at a given rate. A fluid can be classified as Newtonian fluid if the viscosity is constant and independent of shear rate. On the other hand, the viscosity of a non-Newtonian fluid changes with shear rate. Figure 5 shows the variation in viscosity of AAS paste with shear rate at an activator concentration of 3 mol/L and a temperature of 20 °C. It can be seen that there was a continuous reduction in measured viscosity with increasing shear rate at a reducing rate irrespective of the time interval. Therefore, the AAS paste prepared in this study was classified as non-Newtonian fluid. Note that the viscosity of AAS paste measured at different time intervals differed a lot at a given shear rate. For example, when the shear rate was 20 s−1, the viscosity was 6.75 Pa·s after 1 min. The viscosity reduced to 3.42 Pa·s and 3.04 pa·s at the 41 and 81 min, respectively. However, the viscosity increased by 74% when the time interval further increased from 81 min to 121 min. The reversal in measured viscosity can be explained by the fact that the generated hydration products of AAS paste overtook the structural rupture caused by rotor motion, resulting in enhanced deformation resistance. Similar relationships between viscosity and shear rate were obtained at different activator concentrations (i.e. 1 and 2 mol/L) and temperatures (i.e. 10 and 30 °C).
The activation energy in the radiative flow of fourth-grade nanomaterial with convective conditions
Published in Waves in Random and Complex Media, 2022
Based on the relationship between shear stress (tangential stress) and strain rate (deformation rate), fluids are vastly classified into viscous and non-Newtonian. In viscous fluids, shear stress and strain rate are related directly and linearly, while in non-Newtonian fluids shear stress and strain rate are directly related in a non-linear way. Non-Newtonian fluids have applications in technological and industrial sectorssuch as aerospace lubrications, biotechnology polymer processing, nuclear thermo-hydraulic, and automotive vehicle lubrications. Several molten metals and polymer solutions are classified as non-Newtonian fluids. The non-Newtonian fluids include ketchup, paints, blood, oils, mud, starch, and cosmetics such as creams and shampoos, etc. Due to complex rheology, numerous non-Newtonian fluid models were proposed by researchers during the last decades. Non-Newtonian fluids are further sub-classified into rate, differential, and integral-type fluids. These models include Casson, Oldroyd-B, Jeffrey, Maxwell, Burgers, Generalized Burgers, Sisko, Williamson, second-, third-, and fourth-grade fluids, etc. Lenci and Chiapponi [10] experimentally and theoretically investigated flows of non-Newtonian material through aperture fractures. Hayat et al. [11] analytically examined fourth-grade material flow-filling porous medium. The impact of the magnetic field on the rotating flow of Jeffrey material between two cylinders was elaborated by Kumar et al. [12]. Some latest analyses regarding non-Newtonian material can be seen in Refs. [13–22].