CFD study on rise and deformation characteristics of buoyancy-driven spheroid bubbles in stagnant Carreau model non-Newtonian fluids

Gollakota, Anjani R.K.; Kishore, Nanda

doi:10.1007/s00162-017-0436-y

Cited by 8 publications

(5 citation statements)

References 33 publications

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“…A comparison between the theoretical and numerical results of frequency of bubble formation shows that the CLSM is more accurate than the VOF method to reproduce the bubble formation frequency, with a relative error lower than 2%. If the numerical bubble frequency is compared against the extrapolated bubble frequency from the verification study 12.61 (1/s), the relative error (e 21 ext × 100%) is lower than 5%, which shows that the results are in the asymptotic range of convergence. The bubble formation is considered to take place in the dynamic regime according to Mccann and Prince [39] since the flow rate used in this study is near to 3.93 × 10 −6 m 3 /s.…”

Section: Bubble Formation Process From An Orifice Embedded In Water Amentioning

confidence: 90%

“…In this study, the singularities arise when the bubble neck's pinch-off (a finite time singularity in the flow where pressure, velocity, and curvature diverge), consequently this gives non-conservative estimates of discretization errors since the convergence condition (R) [38] corresponds to divergence with R = ε 21 /ε 32 = 10, where ε 21 = φ 2 − φ 1 and ε 32 = φ 3 − φ 2 . Despite that a divergence condition was obtained because of the singularities arising in the study, the verification of numerical accuracy was considered acceptable based on the GCI value and the extrapolated critical variable value (ϕ 21 ext = 12.61 [1/s]). The study was also validated by comparing the numerical values of the bubble frequency against those predicted by the analytical equation reported in [25].…”

Section: Mesh Resolutionmentioning

confidence: 99%

“…Using the regularized function and its preserving of the smooth profile in the reinitialization procedure, the spurious currents and the oscillations in the pressure are not introduced as the interface is advected. The solution of the mass conservation issue of the LS method allows the model to be used successfully in applications such as bubble formation [20], bubble rise [17,18,21] and bubble bursting at the free surface [14], among many others. It is important to remark that new formulations of the conservative level set method has been presented using different reinitialization procedures to improve the robustness of the CLSM [22,23].…”

Section: Introductionmentioning

confidence: 99%

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Computational Study in Bottom Gas Injection Using the Conservative Level Set Method

et al. 2020

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This paper presents a computational study on bottom gas injection in a cylindrical tank. The bubble formation at submerged orifices, bubble rising, and interactions between bubbles and bubbles with the free surface were studied using the conservative level set method (CLSM). Since the gas injection is an important technique in various fields and this process is quite complicated, the scenario was chosen to quantify the efficacy of the CLSM to describe the gas-liquid complex interactions with fast changes in the surface tension force and buoyancy force. The simulation accuracy is verified with the grid convergence index (GCI) approach and Richardson Extrapolation (RE) and is validated by comparing the numerical results with experimental observations, theoretical equations, and published data. The results show that the CLSM accurately reproduces the bubble formation frequency, and that it can handle complicated bubble shapes. Moreover, it captures the challenging phenomena of interaction between bubbles and free surface, the jet of liquid produced when bubbles break through the free surface, and the rupture of the film of liquid. Therefore, the CLSM is a robust numerical technique to describe gas-liquid complex interactions, and it is suited to simulate the gas injection operation.

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Section: Bubble Formation Process From An Orifice Embedded In Water Amentioning

confidence: 90%

Section: Mesh Resolutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Computational Study in Bottom Gas Injection Using the Conservative Level Set Method

et al. 2020

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“…The level set method only needs to solve one transport equation, therefore it is less computational power demanding [12]. Its capabilities were proved in many studies of two phase problems [7], [13]- [17]. These are the main reasons, why Level set method was chosen.…”

Section: Methodsmentioning

confidence: 99%

CFD Simulation of a Sub-Millimeter Rising Bubble in a Stagnant Liquid

Crha¹,

Kašpar²,

Basařová³

2020

Topical Problems of Fluid Mechanics 2020

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Hydrodynamics of the multiphase apparatus is strongly affected by fluids used in the process. One of the main quantities, which determine the hydrodynamic behaviour is the rising velocity of gaseous bubbles. This velocity can be determined easily in small scale apparatuses, but it can be much more challenging in industrial-scale devices. For that reason, mathematical modeling is used. COMSOL Multiphysics, finite element CFD solver, was used to describe the behaviour of the single bubble rising in aqueous solutions of ethanol and n-propanol. Aqueous solutions of low-carbon alcohols are extensively used in many multiphase chemical processes such as distillation, flotation and in multiphase reactors. Bubble velocities and shapes obtained from the simulation were compared to experimental and theoretical values. Two initial diameters of bubbles were used-0.6 and 0.8 mm. Terminal velocities and shapes deformations obtained from COMSOL of 0.6 mm bubble were in an agreement with theoretical and experimental values.

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“…The results from 2D axisymmetrical simulations were also used for a comparison of the results obtained from the 3D simulation. The Level set method implemented in COMSOL Multiphysics has been tested multiple times on various multiphase flow phenomena [9,15,16]. These essential studies have shown the suitability of using the Level set method, but various fluids have not been tested.…”

Section: Introductionmentioning

confidence: 99%

CFD simulation of a small bubble motion in 3D flow domain: effect of liquid density, viscosity and surface tension

Crha

Basařová

Růžička

2022

Preprint

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The motion of small slightly deformed bubbles rising in stagnant liquids was numerically simulated in a fully three-dimensional domain using the commercial CFD (Computational Fluid Dynamics) solver COMSOL Multiphysics. The interface was tracked by the built-in conservative Level set method on a fixed numerical grid. The purpose of this work was to validate the ability of the solver to calculate the single bubble motion in liquids, which differ in surface tension, dynamic viscosity, and density. Experimental data for three liquids and various initial bubble diameters (1–1.6mm) together with the recommended theoretical models were used for validation. Using a 3D domain, very good agreement was obtained both in bubble shape deformations and values of bubble terminal velocity. The best results were achieved for a liquid with low surface tension and low viscosity (1-propanol). In the case of high surface tension and low viscosity liquid (water) the solver underestimates bubble deformation and the bubble velocity. In case of glycerol (high surface tension and viscosity), the low bubble deformation is correctly calculated, but the velocity is underestimated.

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CFD study on rise and deformation characteristics of buoyancy-driven spheroid bubbles in stagnant Carreau model non-Newtonian fluids

Cited by 8 publications

References 33 publications

Computational Study in Bottom Gas Injection Using the Conservative Level Set Method

Computational Study in Bottom Gas Injection Using the Conservative Level Set Method

CFD Simulation of a Sub-Millimeter Rising Bubble in a Stagnant Liquid

CFD simulation of a small bubble motion in 3D flow domain: effect of liquid density, viscosity and surface tension

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