Bubble generated turbulence and direct numerical simulations

Joshi, Jyeshtharaj B.; Nandakumar, K.; Evans, Geoffrey M.; Pareek, Vishnu; Gumulya, Monica; Sathe, Mayur J.; Khanwale, Makrand A.

doi:10.1016/j.ces.2016.03.041

Cited by 47 publications

(13 citation statements)

References 223 publications

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“…CFD has been used as a useful tool for hydrodynamic prediction, design, scale‐up, and optimization of several chemical engineering equipments. Some of the commonly used chemical engineering equipments, that have investigated using CFD so as to understand the underlying flow physics involved are: pipes and pipe bends, particulate flows, packed bed reactors, fluidized bed reactors, bubbly flows, and heat exchangers . CFD has gained a lot of importance in the previous three decades owing to the wide application and promising results, which it offers at a nominal cost.…”

Section: Introductionmentioning

confidence: 99%

Teaching turbulent flow through pipe fittings using computational fluid dynamics approach

Gajbhiye

Kulkarni

Tiwari

et al. 2020

Engineering Reports

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The largest network of fluid transportation in the world is through pipelines.During the transportation of fluids through pipes, several "fittings" are used in the piping system such as elbows, T-junctions, reducers, expanders, bends, couplings, valves, etc. The flow complexities in pipe fittings are accounted for the pressure drop in piping network design. The pressure drop is estimated using the loss coefficient or equivalent length method using standard charts. Computational fluid dynamics (CFD) is a reliable tool to estimate pressure drop and understand nonidealities in pipe fittings. The use of CFD in the advanced level course in transport phenomena/fluid flow for piping network design can help students to implement modern mathematical tools as well as evaluate standard protocols followed in the industries. In this article, an interactive teaching methodology has been implemented to investigate the hydrodynamics in various pipe fittings (elbow, bend, Tee, and reducer) by actually visualizing the flow. The three-dimensional flow visualization is used to demonstrate the nonidealities such as separation, swirling, dead zones, etc. The CFD simulations of pipe fittings provided a new learning experience to the students that would help them to predict the pressure drops in industrial piping network systems. The outcome from the students' survey showed that the proposed CFD methodology assisted them to gain a better understanding of conventional Chemical Engineering subjects of "Transport Phenomena" and "Fluid Dynamics" in an innovative way. K E Y W O R D Scomputational fluid dynamics, head loss coefficient, pipe fittings, turbulence models 1

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Section: Introductionmentioning

confidence: 99%

Teaching turbulent flow through pipe fittings using computational fluid dynamics approach

Gajbhiye

Kulkarni

Tiwari

et al. 2020

Engineering Reports

View full text Add to dashboard Cite

show abstract

“…Moreover, the used apparatus is burdened with its own limitations for the precision of measurement when assessing the location and velocity of particles and individual phases in the three-dimensional space within a given time point. Recently, research tools dedicated, e.g., to studies on multi-phase flows such as DNS (direct numerical simulations) were developed [16,17]. In those tools, turbulent flows are typically modeled applying Euler's method by solving incompressible Navier-Stokes equations, while the transfer of energy adjusted to scale is executed taking into consideration Kolmogorov theory [18,19].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Hydraulic Conditions in Barbotage Reactors on Aeration Efficiency

Kujawiak

Makowska

Mazurkiewicz

2020

Water

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Barbotage reactors such as airlift reactors (ALR) and bubble column reactors (BCR), due to their two-phase flow systems, were investigated in many research papers. In their basic design variants, they are typically used to lift, mix, and aerate liquids, while, when equipped with additional elements in hybrid variants, their individual properties, i.e., lifting, mixing, and aeration of liquids, can significantly change with the same reactor geometry. The object of this study was to develop a hybrid barbotage reactor in various structural design variants. The structure consisted of a barbotage column of 50 mm in diameter, used to transport a water–air mixture outside the reactor (so-called external loop). The installation was additionally equipped with a nozzle in order to improve mixture aeration and circulation efficiency. The nozzle was mounted at various heights of the column pump segment. Additionally, the reactor was equipped with s moving bed in two variants (20% and 40% reactor capacity) in order to determine its effect on the mixture aeration and circulation conditions. Based on the measurement results, aeration curves were prepared for various structural design and column packing variants of the reactor. Properties of the two-phase mixture were determined for both parts—ALR and BCR. Technological and energy parameters of the aeration process were calculated, and the results obtained for the individual structural design variants were compared. It was found that, for the most advantageous design, in terms of aeration efficiency, the aeration nozzle should be placed in the mid-length of the pump segment of the barbotage column, irrespective of the hybrid reactor packing rate with the moving bed. The reactor packing with the moving bed resulted in a decreased mean water velocity in the reactor. For most analyzed structural design variants, the respective packing with the moving bed had no significant effect on aeration efficiency. Only for one structural design variant did the lack of packing significantly improve oxygen levels by as much as approximately 41%.

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“…As summarized extensively by Joshi et al , most of the experimental studies concerning bubble flows in the last few years deal with bubble motion and turbulence in bubble‐column reactors. Also, most existing experimental studies concerning bubble motion coupled with mass transfer, considered only the behavior of a single bubble, e.g., .…”

Section: Introductionmentioning

confidence: 99%

Investigation of Mass Transfer and Hydrodynamics in a Model Bubble Column

2017

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Gas-liquid mass transfer in bubble columns is strongly influenced by the flow field in the column. The underlying transport processes are often the limiting factor. Since bubble columns are widely used in the chemical process industry, it is essential to quantify how the dispersed gas can come into reaction with the liquid phase through gas-liquid mass transfer. CO 2 bubble swarms in a cylindrical model bubble column are considered. Optical measurement methods are used for the nonintrusive measurement of velocity and pH change, resulting from the dissolution of CO 2 in the liquid phase. The mean and fluctuating velocity components in the center plane of the column as well as the time-dependent pH fields in this plane are determined. From these quantities, derived values characterizing the mass transfer from gaseous CO 2 to the liquid phase can be calculated.

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Bubble generated turbulence and direct numerical simulations

Cited by 47 publications

References 223 publications

Teaching turbulent flow through pipe fittings using computational fluid dynamics approach

Teaching turbulent flow through pipe fittings using computational fluid dynamics approach

The Effect of Hydraulic Conditions in Barbotage Reactors on Aeration Efficiency

Investigation of Mass Transfer and Hydrodynamics in a Model Bubble Column

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