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Nanofluidics
Published in Yubing Xie, The Nanobiotechnology Handbook, 2012
Nanofluidics, as implied by its name, is the study of fluids at the nanoscale. Fluids can be Newtonian fluids such as liquid water or non-Newtonian (complex) fluids such as dilute or concentrated polymer solutions. Current research in nanofluidics mainly investigates effects of nanoconfinement on fluid flow and the dynamics of ions, nanoparticles, and molecules (Eijkel and van den Berg 2005; Schoch et al. 2008; Bocquet and Charlaix 2010).
Lattice Boltzmann Simulation of Microstructures
Published in Shyam S. Sablani, M. Shafiur Rahman, Ashim K. Datta, Arun S. Mujumdar, Handbook of Food and Bioprocess Modeling Techniques, 2006
Despite the fact that the lattice Boltzmann scheme has been derived by discretization of kinetic theory, it does not seem significantly different from traditional finite-volume schemes. However, as demonstrated above, the lattice Boltzmann can be distinguished from traditional finite volumes by a number of favorable attributes. In summary: In the case of ω > 1, the lattice Boltzmann schemes make use of gradients in conserved quantities, i.e., density gradient or the symmetric part of the deformation rate tensor, as state variables, making it effectively a higher-order scheme.Fluid flow is solved in the weakly compressible limit using the ideal gas equation of state. This makes it possible to model fluid flow through complex geometries with relatively coarse grids. Traditional schemes based on incompressible fluids have to solve the Poisson equation for the pressure, requiring refined meshes that result in longer computation times. The weakly compressible limit, however, does imply that the use of lattice Boltzmann schemes should be limited to low-Mach-number flows, u/cs ≪ 1 (or rather low Courant numbers, u/c ≪ 1).Lattice Boltzmann schemes are implemented in a stream-and-collide fashion, where the most demanding computations (collision step) needs only local information. This makes it very simple to code and, above all, ideal for parallel computing. Practice shows that the performance scales almost linearly with the number of processors. Consequently, numerous implementations of lattice Boltzmann schemes are found on PC clusters, parallel-computing architectures, or even grid environments.Via its link to kinetic theory, it is relatively simple to extend the lattice Boltzmann to complex fluids that are often described on a thermodynamic basis or on a particulate basis. Examples of these complex fluids to which lattice Boltzmann has been applied are immiscible fluids, surfactant stabilised emulsions, polymer melts, microemulsions, and suspensions.
Flow and heat transfer characteristics of non-Newtonian fluid over an oscillating flat plate
Published in Numerical Heat Transfer, Part A: Applications, 2021
Ailian Chang, Kambiz Vafai, HongGuang Sun
Non-Newtonian fluid flow and heat transfer are important in several different applications. Unlike Newtonian fluid, where the viscous stress is linearly proportional to the strain rate; this cannot describe the rheological behaviors of complex fluids. Non-Newtonian fluids are more common to observe, such as blood, paints, crude oil, drilling fluid, polymeric solutions, etc [1–3]. These fluids play a significant role in biomedical, environmental, chemical and petroleum engineering among others [4, 5]. The complex characteristics of non-Newtonian fluid exhibiting shear thinning and shear thickening are represented within a number of well-established fluid constitutive models [6]. For instance, Balmforth et al. [7] presented the Herschel-Bulkley constitutive law to describe the fluid flow problem. Duffy et al. [8] considered a Carreau model to illustrate the effect of shear thinning and thickening on the displacement thickness. Das et al. [9] developed the Casson fluid model to distinguish the non-Newtonian fluid behavior. Another popular non-Newtonian model, the power-law model also plays an important role in predicting fluid flow behavior [10]. Pascal [11] studied the power-law behavior of non-Newtonian fluids. Jambal et al. [12] analyzed non-Newtonian power-law fluids between parallel plates and circular duct flow. The present study is focused on the study of unsteady flow and heat transfer of non-Newtonian power-law fluid over an oscillation plate which had not been considered in the literature.
Flow and heat transfer characteristics of non-Newtonian fluid over an oscillating flat plate
Published in Numerical Heat Transfer, Part A: Applications, 2021
Ailian Chang, Kambiz Vafai, HongGuang Sun
Non-Newtonian fluid flow and heat transfer are important in several different applications. Unlike Newtonian fluid, where the viscous stress is linearly proportional to the strain rate; this cannot describe the rheological behaviors of complex fluids. Non-Newtonian fluids are more common to observe, such as blood, paints, crude oil, drilling fluid, polymeric solutions, etc [1–3]. These fluids play a significant role in biomedical, environmental, chemical and petroleum engineering among others [4, 5]. The behavior of non-Newtonian fluid exhibiting shear thinning and shear thickening are represented within a number of well-established fluid constitutive models [6]. For instance, Balmforth et al. [7] presented the Herschel-Bulkley constitutive law to describe the fluid flow problem. Duffy et al. [8] considered a Carreau model to illustrate the effect of shear thinning and thickening on the displacement thickness. Das et al. [9] characterized the non-Newtonian fluid behavior through the use of the Casson fluid model. Another popular non-Newtonian model, the power-law model also plays an important role in predicting fluid flow behavior [10]. Pascal [11] studied the power-law behavior of non-Newtonian fluids. Jambal et al. [12] analyzed power-law fluids flow between parallel plates and in circular duct. Present study focused on the unsteady flow and heat transfer of non-Newtonian power-law fluid over an oscillation plate which had not been considered in the literature.
Magnetic dipole dynamics on Reiner–Philippoff boundary layer flow
Published in Numerical Heat Transfer, Part A: Applications, 2023
Yusuf O. Tijani, Adeshina T. Adeosun, Hammed A. Ogunseye, Hari Niranjan
Many fluids of industrial, biomedical, and engineering applications are not in conformity with Newton’s idea of fluid viscosity relation. In these fluids, rheological characterization involves a nonlinear relationship between sheer stress and strain. Fluids such as these (nonlinear sheer stress to strain deformation rate) are considered to be non-Newtonian or complex fluids. Non-Newtonian fluids with non-Newtonian viscosity relation can be categorized into three distinct groups: dilatant (shear-thickening), pseudo-plastic (shear-thinning), and generalized Newtonian fluids.