Vortex Formation and Subsequent Air Entrainment inside a Liquid Pool

Kumar, Parmod; Prajapati, Mihir; Das, Arup Kumar; Mitra, Sushanta K.

doi:10.1021/acs.iecr.8b00379

Cited by 20 publications

(9 citation statements)

References 56 publications

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“…Again, in the same year, they examined the pattern of air filaments in symmetric converging fields by considering the same gas–liquid pair. Kumar et al attempted experimentally to elucidate the interfacial vortex and air penetration caused by an immersed rotary flat circular disc under a liquid bath with the depth of submergence and also predicted the asymmetric structured cusp with the aid of a tilted disc (0–17.45°). In addition to that, Prajapati et el .…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Analytical Prediction on the Development of Entrained Air Filament Caused by the Combined Effect of Rotational Field and Free Stream Flow

Panda

Rana

2022

Ind. Eng. Chem. Res.

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In this study, an attempt has been made to characterize the pattern of entrained air filament inside a liquid bath of high viscosity by employing a fully submerged horizontal rotating solid roller where the lighter phase is allowed to flow uniformly above the bath. The influence of roller rotational speed (ω), depth of submergence (h/D), strength of the crossflow (Re flow ), and fluid pair (Mo) on the entrainment profile has been established numerically to report the physical insights. An open-source Gerris solver has been employed to perform this computational work. We have also described the transient dynamics of the cusp tip for various input pertinent parameters. In addition, both departure of bubbles at the tip of the steady configured cusp and the entrainment rate are predicted for different gas−liquid pairs. Interfacial configurations are also obtained as a consequence of the effect of gravitational pull. Lastly, an analytical analysis predicted successfully the obtaining of the structure of the cusp, and the predictions are quite satisfactory compared to present numerical data.

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Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Analytical Prediction on the Development of Entrained Air Filament Caused by the Combined Effect of Rotational Field and Free Stream Flow

Panda

Rana

2022

Ind. Eng. Chem. Res.

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“…Observations of such a kind of cusp profiles are quite important and relevant to describe the fluidic pattern around the spinning roller in the present investigation. Numerous researchers ,,,,,, attempted to characterize the gaseous cusp profile thoroughly to extract the underlying physics in their studies. Figure illustrates the pattern of radial distance of the cusp from the center of the roller by considering the variation of S / D and Ca .…”

Section: Resultsmentioning

confidence: 99%

“…They revealed that a thicker film and longer cusp are obtained in a highly viscous pool. Kumar et al performed experiments to obtain free surface vortex (FSV) entrainment in the bath using a swirling disk. They revealed the dependence of the vortex profile on the tangential velocity (measured by the Froude number, ) and depth of immersion of the disk.…”

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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“…It is widely accepted that bathtub vortices which form under experimental conditions contain a vortex core where vorticity is non-negligible, resulting from the fluid's viscosity [20,116]. Many authors in the literature have studied this type of fluid flow; for example see [5,6,113] for experimental studies, [33,77,182] for numerical studies and [77,138,192] for analytical studies. Since most of our theoretical discussion has been centred on rotating fluids in shallow water, we will be interested in the component of vorticity which is perpendicular to the free surface.…”

Section: Chapter 5 Vorticitymentioning

confidence: 99%

On the analogy between black holes and bathtub vortices

Patrick

2020

Preprint

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Analogical thinking is a valuable tool in theoretical physics, since it allows us to take the understanding we have developed in one system and apply it to another. In this thesis, we study the analogy between two seemingly unlikely systems: rotating black holes, elusive cosmic entities that push our theoretical understanding of modern physics to its limits, and bathtub vortices, an occurrence so common that they can be observed on a day-to-day basis in almost any household. Despite the clear difference between these two systems, we argue that lessons from each can be used to learn something about the other.We investigate the equivalence between surface wave propagation in shallow water and the propagation of a massless scalar field on an effective spacetime, focussing in particular on the rotating black hole geometry sourced by a rotating draining vortex flow. Using this analogy, we verify for the first time that three effects predicted to occur around rotating black holes also occur in a laboratory experiment. These are superradiance, an energy enhancement process whereby waves extract rotational energy from the system, quasi-normal ringing, describing the relaxation of the system toward equilibrium, and the backreaction, which mediates the exchange of energy between fluctuations and the background they experience.Previous studies within analogue gravity have focussed on demonstrating that the existence of Hawking radiation does not depend on the details of high frequency dispersion. Our experimental results indicate that the same can be said for superradiance and quasi-normal ringing, although notable differences do occur when the medium is dispersive. Using tools originally developed in the context of black hole physics, we propose a new method for flow measurement based on the characteristic ringing frequencies of the vortex, which can be used for a known effective field theory to measure the parameters of the fluid flow, or for known flow parameters to test the effective field theory. We also study how the characteristic mode spectrum is modified by a purely rotating fluid with vorticity, finding that the system can also support bound state resonances characterised by a much longer lifetime than the usual modes.Finally, we demonstrate theoretically and experimentally how the backreaction of waves onto the background flow manifests itself in the bathtub system. This study reveals several interesting features of experimental bathtub vortices, in particular that the presence of waves leads to the removal of fluid mass from the system, leading to a net decrease in the water level. This dynamical interplay between waves and the background makes it a promising candidate for study in the quantum regime, where the spontaneous emission of waves will also influence the system's evolution. I'd also like to thank my house mates Berry, Will, Aron and John. At first, I didn't believe anything could live up to my first four years living in Nottingham as an undergraduate but I have to admit, I was wrong. Thank you all for ...

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Vortex Formation and Subsequent Air Entrainment inside a Liquid Pool

Cited by 20 publications

References 56 publications

Numerical Simulation and Analytical Prediction on the Development of Entrained Air Filament Caused by the Combined Effect of Rotational Field and Free Stream Flow

Numerical Simulation and Analytical Prediction on the Development of Entrained Air Filament Caused by the Combined Effect of Rotational Field and Free Stream Flow

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

On the analogy between black holes and bathtub vortices

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