Lift forces on a cylindrical particle in plane Poiseuille flow of shear thinning fluids

In this study, the gas holdup of bubble swarms in shear-thinning fluids was experimentally studied at superficial gas velocities ranging from 0.001 to 0.02 m·s−1. Carboxylmethyl cellulose (CMC) solutions of 0.2 wt%, 0.6 wt%, and 1.0 wt% with sodium dodecyl sulfate (SDS) as the surfactant were used as the power-law (liquid phase), and nitrogen was used as the gas phase. Effects of SDS concentration, rheological behavior, and physical properties of the liquid phase and superficial gas velocity on gas holdup were investigated. Results indicated that gas holdup increases with increasing superficial gas velocity and decreasing CMC concentration. Moreover, the addition of SDS in CMC solutions increased gas holdup, and the degree increased with the surfactant concentration. An empirical correlation was proposed for evaluating gas holdup as a function of liquid surface tension, density, effective viscosity, rheological property, superficial gas velocity, and geometric characteristics of bubble columns using the experimental data obtained for the different superficial gas velocities and CMC solution concentrations with different surfactant solutions. These proposed correlations reasonably fitted the experimental data obtained for gas holdup in this system.

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Non linear transverse disturbances in plane poiseuille flow at low Reynolds numbers — Part I

Meccanica ◽

10.1007/bf02145651 ◽

1970 ◽

Vol 5 (4) ◽

pp. 270-276

Author(s):

Ettore Bellomo ◽

Maria Morandi Cecchi

Keyword(s):

Poiseuille Flow ◽

Reynolds Numbers ◽

Plane Poiseuille Flow ◽

Low Reynolds Numbers ◽

Non Linear ◽

Low Reynolds

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Stability of Shear-Thickening Liquids Between Rotating Cylinders

Volume 8: Dynamic Systems and Control, Parts A and B ◽

10.1115/imece2010-39854 ◽

2010 ◽

Author(s):

Nariman Ashrafi ◽

Habib Karimi Haghighi

Keyword(s):

Couette Flow ◽

Dynamical Behavior ◽

Shear Thickening ◽

Shear Thinning ◽

Taylor Vortex ◽

Shear Dependent Viscosity ◽

Shear Thinning Fluids ◽

Shear Thickening Fluids ◽

The Stability ◽

Dependent Viscosity

The effects of nonlinearities on the stability are explored for shear thickening fluids in the narrow-gap limit of the Taylor-Couette flow. It is assumed that shear-thickening fluids behave exactly as opposite of shear thinning ones. A dynamical system is obtained from the conservation of mass and momentum equations which include nonlinear terms in velocity components due to the shear-dependent viscosity. It is found that the critical Taylor number, corresponding to the loss of stability of Couette flow becomes higher as the shear-thickening effects increases. Similar to the shear thinning case, the Taylor vortex structure emerges in the shear thickening flow, however they quickly disappear thus bringing the flow back to the purely azimuthal flow. Naturally, one expects shear thickening fluids to result in inverse dynamical behavior of shear thinning fluids. This study proves that this is not the case for every point on the bifurcation diagram.

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