A pair of bubbles’ rising dynamics in a xanthan gum solution: a CFD study

RSC Advances ◽  
2015 ◽  
Vol 5 (11) ◽  
pp. 7819-7831 ◽  
Author(s):  
Md. Tariqul Islam ◽  
P. Ganesan ◽  
Ji Cheng
Keyword(s):  
Rheological Properties ◽  
Newtonian Fluid ◽  
Xanthan Gum ◽  
Volume Of Fluid ◽  
Volume Of Fluid Method ◽  
Xanthan Gum Solution

The motion and interaction of a bubble pair in a non-Newtonian fluid are numerically simulated by a volume of fluid method. The effects of initial horizontal bubble interval, oblique alignment and fluid rheological properties on the pair of rising bubbles are evaluated.

scholarly journals Effects of Xanthan gum on rheological properties of Aloe vera-Moringa leaf juice blends

2021 ◽  
Vol 47 (2) ◽  
pp. 583-596
Author(s):  
Victor V Matabura ◽  
Leonard MP Rweyemamu
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Newtonian Fluid ◽  
Xanthan Gum ◽  
Aloe Vera ◽  
Flow Behaviour ◽  
Bingham Model ◽  
Flow Behaviour Index ◽  
Model Equations ◽  
Leaf Juice

Understanding the impacts of hydrocolloid agents on the rheological properties of nutraceutical beverages like Aloe vera-moringa juice blend is very useful for functional properties and product stability. To this end, the effects of xanthan gum on rheological properties in Aloe vera-moringa leaf juice blends were investigated using a Brookfield rheometer. Aloe vera-moringa leaf juice blends were prepared and then incorporated with xanthan gum at different ratios (w/w) of 0.2%, 0.4%, 0.6%, 0.8%, and 1%. The results revealed that the viscosity of Aloe vera-moringa juice blend was strongly affected by the xanthan gum addition. The viscosity profiles depicted a decreasing trend in viscosity when a shear rate increased. The Aloe vera-moringa leaf juice blend changes from a Newtonian fluid to the non-Newtonian fluid as the xanthan gum fraction increases. Moreover, shear stress was observed to increase with increasing in xanthan gum concentrations. For quantitative analysis, both Power-law and Bingham model equations were fitted to experimental data to easily describe the flow behaviour of the Aloe vera-moringa leaf juice blends. The juices added with xanthan gum of 0.4% to 1% were found to show a shear-thinning behaviour, since the flow behaviour index, n < 1. This implies that the apparent viscosity decreases as the shear rate increases. Keywords: Aloe vera juice, Moringa leaf juice, Xanthan gum, Rheological property, Nutraceutical beverage

An Experimental Study on Heat Transfer Enhancement of Non-Newtonian Fluid in a Rectangular Channel With Dimples/Protrusions

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Di Zhang ◽  
Lu Zheng ◽  
Gongnan Xie ◽  
Yonghui Xie
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Newtonian Fluid ◽  
Xanthan Gum ◽  
Rectangular Channel ◽  
Transfer Enhancement ◽  
Cooling Channels ◽  
Nusselt Numbers ◽  
Mass Fractions ◽  
Xanthan Gum Solution

Dimple and protrusion play important roles in the heat transfer enhancement and flow characteristic in cooling channels, which widely employed within electronic cooling systems. Non-Newtonian fluid has significant differences with Newtonian fluid, such as water, in fluid characteristic. In this study, an experiment on the viscosity of three different kinds of non-Newtonian fluids, i.e., xanthan gum solution, Carbopol 934 solution, polyacrylamide solution, was first accomplished to acquire the viscosity with different mass fractions. Then, experimental measurements on heat transfer and friction characteristics of non-Newtonian fluid in a rectangular channel with dimples and protrusions were conducted. The overall Nusselt numbers (Nu) and Fanning friction factors at different dimple/protrusion structures were obtained with various inlet flow rates and mass fractions. The results show that only xanthan gum solution has the significant shear thinning effect within the concentration range of this study, and the dimples/protrusions both have great effect on the heat transfer enhancement in the rectangular channel, and that the heat transfer of the case with the protrusions and crossing arrangement can be further enhanced with the higher Nu when compared to the case with the dimples and aligned arrangement. Moreover, an increase in Nu with the higher non-Newtonian fluid mass fraction is observed.

Rheological Properties of Methane Hydrate Slurry in the Presence of Xanthan Gum

SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2341-2352 ◽  
Author(s):  
Weiqi Fu ◽  
Zhiyuan Wang ◽  
Baojiang Sun ◽  
Jianchun Xu ◽  
Litao Chen ◽  
...  
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Newtonian Fluid ◽  
Methane Hydrate ◽  
Xanthan Gum ◽  
Drilling Fluid ◽  
Hydrate Formation ◽  
Shear Thinning ◽  
Shear Rates ◽  
Blowout Preventer

Summary Methane hydrate formation in a xanthan-gum (XG) solution is an important problem for drilling in a deepwater environment. It not only alters the rheology of the drilling fluid in the wellbore but increases the risks of a hydrate blockage in the blowout preventer. The current work is performing groups of experiments to investigate the rheology of the hydrate slurry under XG concentrations of 0.15, 0.2, 0.25, and 0.3%, shear rates from 10 to 480 s−1, and hydrate concentrations from 1.01 to 9.12%. The experimental results show that the hydrate slurry with XG additives exhibits an obvious shear-thinning behavior, which is because the XG solution has strong pseudoplastic characteristics, and the inner structures of the flocculated hydrate particles suspended in the hydrate slurry are broken up during the hydrate-slurry flow. The increase of hydrate concentrations in the hydrate slurry can reduce the non-Newtonian fluid index and make the rheology of the hydrate slurry become more shear-thinning. However, as the XG concentration increases in the hydrate slurry, the influence of the hydrate concentration on the rheology of the hydrate slurry gradually weakens. Empirical Herschel–Bulkley-type equations are developed to describe the rheology of the hydrate slurry with XG for the current experimental condition, considering the shear rate, hydrate concentration, and XG concentration. In the proposed equations, the non-Newtonian factor and the consistency factor are expressed as functions of XG concentration empirically. Correction Notice:The preprint version of this paper was modified from its original version to correct Figs. 8 and 9 and Eqs. 6 through 9 on page 7. Errata explaining the corrections are included below as Supporting Information.

Interaction Between Multiple Solid Objects and Bubbles

2010 ◽  
Author(s):  
Ryuichi Iwata ◽  
Takeo Kajishima ◽  
Shintaro Takeuchi
Keyword(s):  
Numerical Method ◽  
Volume Of Fluid ◽  
Solid Particles ◽  
Immersed Boundary ◽  
Particle Interactions ◽  
Volume Of Fluid Method ◽  
Rising Bubble ◽  
Solid Objects ◽  
Multiple Particles ◽  
Particle Laden Flows

In the present study, bubble-particle interactions in suspensions are investigated by a coupled immersed-boundary and volume-of-fluid method (IB-VOF method), which is proposed by the present authors. The validity of the numerical method is examined through simulations of a rising bubble in a liquid and a falling particle in a liquid. Dilute particle-laden flows and a gas-liquid-solid flow involving solid particles and bubbles of comparable sizes to one another (Db/Dp = 1) are simulated. Drag coefficients of particles in particle-laden flows are estimated and flow fields involving multiple particles and a bubble are demonstrated.

scholarly journals Adjoint complement to the volume-of-fluid method for immiscible flows

2021 ◽  
pp. 110411
Author(s):  
Niklas Kühl ◽  
Jörn Kröger ◽  
Martin Siebenborn ◽  
Michael Hinze ◽  
Thomas Rung
Keyword(s):  
Volume Of Fluid ◽  
Volume Of Fluid Method ◽  
Immiscible Flows
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