Effects of Contamination and Shear-Thinning Fluid Viscosity on Drag Behavior of Spherical Bubbles

2013 ◽  
Vol 52 (17) ◽  
pp. 6049-6056 ◽  
Author(s):  
Nanda Kishore ◽  
V. S. Nalajala ◽  
Raj P. Chhabra
2012 ◽  
Vol 39 (3) ◽  
pp. 209-231 ◽  
Author(s):  
Shankar Mandal ◽  
Swati Mukhopadhyayy ◽  
G.C.Z. Layek

This paper aims to investigate the blood flow in a bell-shaped constricted rigid tube, modeled as stenosed artery. The flow is assumed to be axi-symmetric, laminar and of oscillatory type. A mathematical model of shear-thinning fluid corresponding to the shear-dependent blood viscosity (mainly due to the behavior of the red blood cells in suspension of the flowing blood) is considered. The governing equations of motion are presented with the help of stream function-vorticity and are solved numerically by finite-difference technique. The shear-thinning fluid model for the flowing blood has significant contribution in the dynamics of oscillatory blood flow. The results reveal that the arterial wall shear stress reduced significantly and the peak value of the wall shear stress at the maximum area reduction is comparatively low for Newtonian fluid viscosity. The lengths of recirculating regions formed after the constriction are reduced for the shear-thinning blood viscosity model and also for its different material parameters.


Soft Matter ◽  
2021 ◽  
Author(s):  
Ke Qin ◽  
Zhiwei Peng ◽  
Ye Chen ◽  
Herve Nganguia ◽  
Lailai Zhu ◽  
...  

Some micro-organisms and artificial micro-swimmers propel at low Reynolds numbers (Re) via the interaction of their flexible appendages with the surrounding fluid. While their locomotion have been extensively studied with...


2017 ◽  
Vol 96 (6) ◽  
Author(s):  
Herve Nganguia ◽  
Kyle Pietrzyk ◽  
On Shun Pak

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 335
Author(s):  
Anna Yagodnitsyna ◽  
Alexander Kovalev ◽  
Artur Bilsky

Immiscible liquid–liquid flows in microchannels are used extensively in various chemical and biological lab-on-a-chip systems when it is very important to predict the expected flow pattern for a variety of fluids and channel geometries. Commonly, biological and other complex liquids express non-Newtonian properties in a dispersed phase. Features and behavior of such systems are not clear to date. In this paper, immiscible liquid–liquid flow in a T-shaped microchannel was studied by means of high-speed visualization, with an aim to reveal the shear-thinning effect on the flow patterns and slug-flow features. Three shear-thinning and three Newtonian fluids were used as dispersed phases, while Newtonian castor oil was a continuous phase. For the first time, the influence of the non-Newtonian dispersed phase on the transition from segmented to continuous flow is shown and quantitatively described. Flow-pattern maps were constructed using nondimensional complex We0.4·Oh0.6 depicting similarity in the continuous-to-segmented flow transition line. Using available experimental data, the proposed nondimensional complex is shown to be effectively applied for flow-pattern map construction when the continuous phase exhibits non-Newtonian properties as well. The models to evaluate an effective dynamic viscosity of a shear-thinning fluid are discussed. The most appropriate model of average-shear-rate estimation based on bulk velocity was chosen and applied to evaluate an effective dynamic viscosity of a shear-thinning fluid. For a slug flow, it was found that in the case of shear-thinning dispersed phase at low flow rates of both phases, a jetting regime of slug formation was established, leading to a dramatic increase in slug length.


2004 ◽  
Vol 59 (2) ◽  
pp. 417-424 ◽  
Author(s):  
Eric Lee ◽  
June-Kuo Ming ◽  
Jyh-Ping Hsu

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