Entrainment in multifluid systems, and rotation induced occurrences

Panda, Santosh Kumar; Rana, Basanta Kumar; Kumar, Parmod

doi:10.1016/j.euromechflu.2022.08.001

Cited by 11 publications

(2 citation statements)

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“…The rotational flux across the interface of the fluid pair causes fluid entrainment, which leads to the enhancement of transfer of mass, momentum, and energy by improving the area of the phase boundary. Such studies not only explore the fundamental aspects but also are quite relevant to several industrial applications − (roll coaters, inkjet printers, decorative or protective materials to metal sheets, and roll oceanic mixed layer). The first investigation in this direction was initiated by Tharmalingam and Wilkinson, and they revealed the influence of the strength of the rotational field on the flow pattern around the roller for various gas–liquid pairs using a capacitance probe.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Air Entrainment Using a Pair of Vertically Aligned Revolving Rollers

Panda

Rana

2023

Ind. Eng. Chem. Res.

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The present study reports the characterization of air entrainment within a viscous liquid pool using a pair of revolving rollers. The rollers are aligned vertically. The top roller (first roller) is partially submerged with a fixed submergence ratio of 0.5 (equally submerged in the gas and liquid); however, the bottom roller (second roller) is fully immersed inside the liquid pool. The present computational work is carried out using opensource Gerris Solver, which discretizes the working domain adaptively based on the gradient of volume fraction. The influence of the rotational speed (described by the capillary number, Ca) and depth of immersion of the second roller (W/D) on the length and width of the entrained cusp is analyzed thoroughly. A scattered regime plot is provided to describe the different patterns of entrainment with the effect of both Ca and W/D. In addition, we have also elucidated the instantaneous (Y*) and maximum (Y max * ) vertical shift of the cusp tip by varying Ca and W/D. An interesting bubble pinch-off mechanism at the cusp tip after achieving the steady length is elucidated by characterizing the frequency and volume accumulation of the detached gaseous masses. The influence of the gravitational pull and viscous drag on the pattern of entrainment is also investigated. They play important roles in controlling the behavior of cusp entrainment. Lastly, an analytical formulation is established to predict the bent thickness of the cusp by employing a balance of the relevant influencing forces acting on the cusp. It provides an excellent agreement between the analytical solutions and computational results.

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Section: Introductionmentioning

confidence: 99%

Characterization of Air Entrainment Using a Pair of Vertically Aligned Revolving Rollers

Panda

Rana

2023

Ind. Eng. Chem. Res.

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“…Dynamics of liquid coatings and entrainment is widely seen in both natural − and many industrial operations. − Specifically, the phenomenon of film flow and entrainment dynamics caused by the external rotational flux using a revolving drum(s) across the gas–liquid interface has remained challenging and popular among researchers − because there is a considerable improvement in exchange of mass, momentum, and energy with the expansion of interfacial area. It is needless to mention here that these investigations reveal the fundamental content of fluid dynamics as well as applicability for several industrially important processes.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Immersion Ratio of a Revolving Roller on the Film Coating and Entrainment Dynamics

Panda

Rana

2023

Ind. Eng. Chem. Res.

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The present study reports a thorough physical understanding of the film coating and air cusp entrainment dynamics in a viscous liquid pool caused by a partially immersed revolving roller. A wide range of submergence ratios of the roller are considered to understand the detailed insightful physics. The dimensionless form of the submergence ratio is defined as the ratio of the height immersion to the diameter of the roller (S/D). Finite volume-based open-source Gerris is employed to carry out the numerical simulations. Furthermore, several influencing parameters such as roller speed (measured by the capillary number, Ca), submergence ratio (S/D), strength of gravitational pull (described by using the Archimedes number, Ar), and strength of the viscous drag (determined by using the Morton number, Mo) are employed to characterize the behavior of film thickness (h*), height of the liquid cusp (Y s *), width of the air cusp (H*), and depth of the entrainment (θ*) thoroughly. Two distinguished regimes are identified at the critical capillary number (Ca c ) by carrying out a meticulous analysis of computational results. Again, the travel rate of the film tip from the receding to the advancing junction is predicted, and a slower travel rate of the film tip is found at a greater S/ D than at a lower value. The behavior of bubble ejection at the cusp tip forms an engrossing bubble train, and the ejection frequency shows a strong dependency on Ca and S/D. We have also proposed various correlations to predict the film thickness, cusp width, and cusp length. The correlations show satisfactory agreement within ±5% of computational data points.

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