Computational Fluid Dynamics (CFD) analysis for the flow of Non-Newtonian and gas-Non-Newtonian liquid through elbows is presented. The commercial software Fluent 6.3 has been used for the simulation. Laminar Non-Newtonian pseudoplastic power law model has been used for the simulation of Non-Newtonian liquid flow through elbows. For two-phase flow Elurian-Elurian approach has been used for simulation. The CFD analysis have been tested from our previously published experimental results, Bandyopadhyay and Das (2007), Bandyopadhyay et al. (2000).

In the present study, the motion of Newtonian and Non-Newtonian liquid drops has been investigated experimentally. In order to investigate the effect of bulk fluid on drops, we have used water and air, as two fluids with different properties, and various industrial and biological applications. Image processing is utilized to analyze the images obtained by a high speed camera. The research has been separated into two parts. The first part has been devoted to the experiments in which air is the bulk fluid, and the second is related to the experiment carried out in water. The range of Reynolds number is, approximately, 50<Re<500. The major concern of the present study is the size variation of drops and its effect on the drag coefficient. It is proved that the period of size variation of a drop does not vary with properties. Rheological aspects of the problem have also been considered. In air with small density and viscosity, addition of Non-Newtonian characteristics to the fluid causes the behavior of the drop to undergo dramatic changes. However, in water, a denser and more viscous bulk fluid, the behavior of Newtonian and Non-Newtonian drops (at least for shear thinning fluids) looks the same.

Kelvin-Helmholtz instability is a hydrodynamic instability generated by the relative motion of immiscible, irrotational, incompressible, and inviscid fluids. In the present study, the Kelvin-Helmholtz instability is assessed for Newtonian and Non-Newtonian fluids by solving two-dimensional Navier-Stokes equations using the finite volume method. ANSYS FLUENT software is used to simulate the two-phase flow field. The numerical method is the finite volume method. Using the semi-implicit method for pressure-linked equations algorithm, the velocity and pressure fields are coupled and the Navier-Stokes equations are solved. The second-order upwind method is used to discretize the convection terms in Navier-Stokes equations and the central difference method is employed to approximate the time derivative. In the case of Newtonian fluids, it was found that for  the growth rate of Kelvin-Helmholtz instability depends on the surface tension when the surface tension is in the range of 0.000192-0.000993 N/m. The results demonstrate that the critical wavenumber is enhanced by increasing the power-law index (n) for shear-thinning and shear-thickening Non-Newtonian fluids; however, at a specific time, the amount of critical wavenumber for shear-thickening fluids is smaller than that for shear-thinning ones. It is also concluded that as the power-law index increases, the wave stability can be reached more rapidly.

Metastasis is the main origin of epithelial cancer-based mortality. Since circulating tumor cells (CTCs) are valid biomarkers to diagnose cancer, their isolation and analysis are crucial. Microfluidic technology has experienced remarkable potential to isolate CTCs due to its unique characteristics. The present paper analyzes the influences of Newtonian and Non-Newtonian fluids on the continuous separation of CTCs using standing surface acoustic waves (SSAWs). The impacts of inlet velocity, oscillation amplitude, dynamic viscosity, CTC radius, power-law index, and sheath-to-sample flow velocity ratio on the isolation process are examined. The results demonstrate that the separation efficiency declines from 88% to 84% by augmenting the inlet velocity from 1.8 mm/s to 2 mm/s. It is found that for a certain value of CTC radius, the amount of sheath flow velocity can be changed to reach a maximum separation efficiency. Besides, the amount of separation efficiency decreases as the dynamic viscosity of the Newtonian fluid is enhanced and the power-law index of the Non-Newtonian fluid is reduced.

The excellent performance of fluidized bed heat exchangers is due to the interaction between particles and heat transfer surface and to the mixing effects in the viscous sublayer. In this paper, the results of experimental investigations on heat transfer for a wide range of Newtonian and Non-Newtonian (shear-thinning power law) fluids are presented. New design equations have been developed for the prediction of heat transfer coefficient. The predictions of these correlations and of numerous correlations recommended by other authors are compared with a large database compiled from the literature.

The mixing of Newtonian and Non-Newtonian fluids in a magnetic micro-mixer was studied numerically using 𝐹 𝑒 3𝑂 4 ferrofluid. The mixing process was performed in a three-dimensional steady-state micro-mixer. A magnetic source was mounted at the entrance of the micro-channel to oscillate the magnetic particles. The effects of electric current, inlet velocity, size of magnetic particles, and Non-Newtonian fluid were examined on the mixing efficiency. It was demonstrated that the mixing efficiency would increase with applied current and the size of magnetic particles. The inlet velocity has an inverse effect on the enhancement of the mixing efficiency. It is found that electric currents of 0A and 50A would lead to the mixing efficiency of 10% and 83%, respectively. In addition, the results of the present work revealed that the mixing efficiency of a Non-Newtonian fluid (blood) is smaller than that of a Newtonian one.

Passive and active separation of microparticles has great importance in biological analysis, diagnostics, chemical processing, etc. Acoustofluidic separation is an active technique employed to isolate or sort micron-sized particles continuously. This technique has lower power consumption compared to other active approaches. Besides, it has good biocompatibility. In this review, recent advances in acoustofluidic particle separation are discussed. Bulk Acoustic Waves (BAWs) and Surface Acoustic Waves (SAWs) are introduced and the effective forces in Newtonian and Non-Newtonian fluids are defined. It is revealed that SAW transducers have several advantages for the separation of particles in comparison with BAW ones. This review demonstrates that Polydimethylsiloxane (PDMS) is widely used to fabricate microfluidic devices in which acoustic waves are employed for sorting and manipulating microparticles. Different investigations considered the separation of microparticles by acoustic waves are compared and their characteristics are determined. Besides, the challenges and perspectives of the field are analyzed and discussed.