The flow of non-Newtonian fluids around bubbles and its connection to the jump discontinuity

Herrera-Velarde, J. Ramon; Zenit, Roberto; Chehata, Daniel; Mena, B.

doi:10.1016/s0377-0257(03)00055-7

Cited by 62 publications

(68 citation statements)

References 12 publications

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“…7) To that end, the rise of gas bubbles in polymer solutions has been the subject of several experimental studies in the past. [8][9][10] Through such studies it has already been established that in viscoelastic liquids rising bubbles develop a cusp at their trailing edge.…”

Section: Introductionmentioning

confidence: 99%

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On the Use of SPH Method for Simulating Gas Bubbles Rising in Viscoelastic Liquids

Vahabi

Sadeghy

2015

J. Soc. Rheol., Jpn

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The upward motion and deformation of a single large-scale two-dimensional planar gas bubble rising in an otherwise quiescent viscoelastic liquid obeying the Oldroyd-B rheological model is numerically investigated using the weakly-compressible smoothed particle hydrodynamics (WC-SPH) method. It is shown that unlike the incompressible version of this mesh-less method (I-SPH), the WC-SPH method combined with the continuum surface force (CSF) idea for modelling surface tension is well capable of capturing the cusped-shape trailing edge during its rise in viscoelastic liquids. The failure of the I-SPH method for predicting the cusp is attributed to the several stages of weighted arithmetic and harmonic interpolations used for smoothing the transport parameters of the constituents. The WC-SPH code developed in the present work has enabled us to obtain results at high density and viscosity ratios not reported in similar works. The results suggest that WC-SPH is better suited than I-SPH for handling bubble rise problem in viscoelastic liquids even at large density and viscosity ratios typical of underwater explosions.

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Section: Introductionmentioning

confidence: 99%

“…[8][9][10] Tracking large bubbles during its rise in non-Newtonian fluids is not an easy experimental task (particularly over large distances). Thus, it should not be surprising that numerical simulations have played a key role in furthering our knowledge in this area.…”

Section: Introductionmentioning

confidence: 99%

On the Use of SPH Method for Simulating Gas Bubbles Rising in Viscoelastic Liquids

Vahabi

Sadeghy

2015

J. Soc. Rheol., Jpn

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“…The flow field behind the bubble reverses direction. This phenomenon was first observed by [23] and was directly related to the appearance of the velocity discontinuity by [14,19,22].…”

Section: Introductionmentioning

confidence: 73%

“…It has been observed that when a bubble or a drop moves, as a result of gravity, in a viscoelastic shear-thinning fluid, a velocity discontinuity phenomenon appears [14][15][16][17][18][19]. When the bubble or drop reaches a certain critical size, its terminal speed increases sharply.…”

Section: Introductionmentioning

confidence: 99%

“…The sudden increase has not been understood fully until recently [17]: a combination of effects has to occur simultaneously. First the viscoelastic nature of the outside liquid induces a change in shape of the drop or bubble, forming a characteristic cusped shape [14,15,[19][20][21]; resulting from this change of shape, the drag coefficient of the object is reduced. Consequently, the speed increases, which, given the shear-thinning properties, will cause the viscosity around the object to decrease, causing an even further rising velocity increase.…”

Section: Introductionmentioning

confidence: 99%

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Encapsulation of Droplets Using Cusp Formation behind a Drop Rising in a Non-Newtonian Fluid

Poryles

Zenit

2018

Fluids

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Abstract:The rising of a Newtonian oil drop in a non-Newtonian viscous solution is studied experimentally. In this case, the shape of the ascending drop is strongly affected by the viscoelastic and shear-thinning properties of the surrounding liquid. We found that the so-called velocity discontinuity phenomena is observed for drops larger than a certain critical size. Beyond the critical velocity, the formation of a long tail is observed, from which small droplets are continuously emitted. We determined that the fragmentation of the tail results mainly from the effect of capillary effects. We explore the idea of using this configuration as a new encapsulation technique, where the size and frequency of droplets are directly related to the volume of the main rising drop, for the particular pair of fluids used. These experimental results could lead to other investigations, which could help to predict the droplet formation process by tuning the two fluids' properties, and adjusting only the volume of the main drop.

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Flow and mass transfer of fully resolved bubbles in non‐Newtonian fluids

2007

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In this work, high-resolution 2-D numerical simulations were performed on the motion of deformable bubbles in non-Newtonian fluids and the associated mass transfer. For that purpose, we have implemented a semi-Lagrangian advection scheme and improved the fluid dynamic calculation by the usage of implicit algorithms. Non-Newtonian fluids are described by generalized Newtonian as well as viscoelastic model fluids. As shear-thinning model we use a Power-Law and a Carreau-Yasuda model, the viscoelastic fluid simulations are based on an Upper-Convected Maxwell model combined with a recently introduced model for the evolution of the effective shear rate. The mathematical challenges arising from the hyperbolic nature of the resulting set of equations are addressed by inclusion of artificial diffusion in the stress equation. In our work, it was found that shear thinning effects have impact on collision rates, and therefore, may influence coalescence of bubbles in non-Newtonian liquids. Furthermore, for the first time, concentration fields of dissolved gas in viscoelastic fluids are presented. The study shows that the fluid elasticity plays a major role for bubble rise velocity, and therefore, mass transfer. As the wake dynamics differ significantly from that in Newtonian liquids, abnormal mixing characteristics can be expected in the bubbly flow of viscoelastic fluids. 2007 American Institute of Chemical Engineers AIChE J, 53: [1861][1862][1863][1864][1865][1866][1867][1868][1869][1870][1871][1872][1873][1874][1875][1876][1877][1878] 2007 Keywords: numerical simulation, bubbles, non-Newtonian liquids, mass transfer IntroductionBecause of persistent uncertainties in the underlying models and system properties, the scale-up of bioreactors remains a challenging problem. For example, the rheology of media in bioreactors is non-Newtonian in most cases. [1][2][3][4][5][6][7][8] However, details of the non-Newtonian fluid characteristics, such as viscoelasticity or the tendency for shear thinning, are frequently unknown or neglected. Furthermore, in contrast to Newtonian media, there is a lack of general correlations for mass and heat transfer rates, which are needed for the prediction of oxygen supply and heat removal. Similar observations can be made for the properties needed to precisely predict transport of metabolites, nutrients, or CO 2 . So far, most studies are based on experimental investigations, which are usually interpreted with simple theoretical models. 3,4,[8][9][10][11] principles methods to predict mass-transfer coefficients, transport rates, and other parameters in non-Newtonian fluids have not been reported so far. Local mass transfer is not the only micro-effect of central importance in the design of bioreactors. Knowledge of the localized forces, such as shear and normal stresses in the cell's microenvironment, is also a key for determining whether a bioreactor is suitable to handle sensitive biosystems.12 Subcritical shear stresses found in the hydrodynamic environment of large-scale reactors may redu...

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The flow of non-Newtonian fluids around bubbles and its connection to the jump discontinuity

Cited by 62 publications

References 12 publications

On the Use of SPH Method for Simulating Gas Bubbles Rising in Viscoelastic Liquids

On the Use of SPH Method for Simulating Gas Bubbles Rising in Viscoelastic Liquids

Encapsulation of Droplets Using Cusp Formation behind a Drop Rising in a Non-Newtonian Fluid

Flow and mass transfer of fully resolved bubbles in non‐Newtonian fluids

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