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Article ; Online: Pair dispersion of turbulent premixed flame elements.

Chaudhuri, Swetaprovo

Physical review. E, Statistical, nonlinear, and soft matter physics

2015 Volume 91, Issue 2, Page(s) 21001

Abstract: Flame particles are mathematical points comoving with a reacting isoscalar surface in a premixed flame. In this Rapid Communication, we investigate mean square pair separation of flame particles as a function of time from their positions tracked in two ... ...

Abstract	Flame particles are mathematical points comoving with a reacting isoscalar surface in a premixed flame. In this Rapid Communication, we investigate mean square pair separation of flame particles as a function of time from their positions tracked in two sets of direct numerical simulation solutions of H(2)-air turbulent premixed flames with detailed chemistry. We find that, despite flame particles and fluid particles being very different concepts, a modified Batchelor's scaling of the form 〈\|Δ(F)(t)-Δ(F)(0)\|(2)〉=C(F)(〈ɛ〉(0)(F)Δ(0)(F))(2/3)t(2) holds for flame particle pair dispersion. The proportionality constant, however, is not universal and depends on the isosurface temperature value on which the flame particles reside. Following this, we attempt to analytically investigate the rationale behind such an observation.
Language	English
Publishing date	2015-02
Publishing country	United States
Document type	Journal Article
ISSN	1550-2376
ISSN (online)	1550-2376
DOI	10.1103/PhysRevE.91.021001
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Article: An opinion on the multiscale nature of Covid-19 type disease spread.

Chaudhuri, Swetaprovo / Saha, Abhishek / Basu, Saptarshi

Current opinion in colloid & interface science

2021 Volume 54, Page(s) 101462

Abstract: Recognizing the multiscale, interdisciplinary nature of the Covid-19 transmission dynamics, we discuss some recent developments concerning an attempt to construct a disease spread model from the flow physics of infectious droplets and aerosols and the ... ...

Abstract	Recognizing the multiscale, interdisciplinary nature of the Covid-19 transmission dynamics, we discuss some recent developments concerning an attempt to construct a disease spread model from the flow physics of infectious droplets and aerosols and the frequency of contact between susceptible individuals with the infectious aerosol cloud. Such an approach begins with the exhalation event-specific, respiratory droplet size distribution (both airborne/aerosolized and ballistic droplets), followed by tracking its evolution in the exhaled air to estimate the probability of infection and the rate constants of the disease spread model. The basic formulations and structure of submodels, experiments involved to validate those submodels, are discussed. Finally, in the context of preventive measures, respiratory droplet-face mask interactions are described.
Language	English
Publishing date	2021-05-01
Publishing country	England
Document type	Journal Article ; Review
ZDB-ID	2019683-0
ISSN	1359-0294
ISSN	1359-0294
DOI	10.1016/j.cocis.2021.101462
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Article ; Online: Mean-field model of synchronization for open-loop, swirl controlled thermoacoustic system.

Singh, Samarjeet / Kumar Dutta, Ankit / Dhadphale, Jayesh M / Roy, Amitesh / Sujith, R I / Chaudhuri, Swetaprovo

Chaos (Woodbury, N.Y.)

2023 Volume 33, Issue 4

Abstract: Open-loop control is known to be an effective strategy for controlling self-excited periodic oscillations, known as thermoacoustic instability, in turbulent combustors. Here, we present experimental observations and a synchronization model for the ... ...

Abstract	Open-loop control is known to be an effective strategy for controlling self-excited periodic oscillations, known as thermoacoustic instability, in turbulent combustors. Here, we present experimental observations and a synchronization model for the suppression of thermoacoustic instability achieved by rotating the otherwise static swirler in a lab-scale turbulent combustor. Starting with the state of thermoacoustic instability in the combustor, we find that a progressive increase in the swirler rotation rate leads to a transition from the state of limit cycle oscillations to the low-amplitude aperiodic oscillations through a state of intermittency. To model such a transition while also quantifying the underlying synchronization characteristics, we extend the model of Dutta et al. [Phys. Rev. E 99, 032215 (2019)] by introducing a feedback between the ensemble of phase oscillators and the acoustic. The coupling strength in the model is determined by considering the effect of the acoustic and swirl frequencies. The link between the model and experimental results is quantitatively established by implementing an optimization algorithm for model parameter estimation. We show that the model is capable of replicating the bifurcation characteristics, nonlinear features of time series, probability density function, and amplitude spectrum of acoustic pressure and heat release rate fluctuations at various dynamical states observed during the transition to the state of suppression. Most importantly, we discuss the flame dynamics and demonstrate that the model without any spatial inputs qualitatively captures the characteristics of the spatiotemporal synchronization between the local heat release rate fluctuations and the acoustic pressure that underpins a transition to the state of suppression. As a result, the model emerges as a powerful tool for explaining and controlling instabilities in thermoacoustic and other extended fluid dynamical systems, where spatiotemporal interactions lead to rich dynamical phenomena.
Language	English
Publishing date	2023-04-05
Publishing country	United States
Document type	Journal Article
ZDB-ID	1472677-4
ISSN	1089-7682 ; 1054-1500
ISSN (online)	1089-7682
ISSN	1054-1500
DOI	10.1063/5.0136385
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Article: Analyzing the dominant SARS-CoV-2 transmission routes toward an

Chaudhuri, Swetaprovo / Basu, Saptarshi / Saha, Abhishek

Physics of fluids (Woodbury, N.Y. : 1994)

2020 Volume 32, Issue 12, Page(s) 123306

Abstract: Identifying the relative importance of the different transmission routes of the SARS-CoV-2 virus is an urgent research priority. To that end, the different transmission routes and their role in determining the evolution of the Covid-19 pandemic are ... ...

Abstract	Identifying the relative importance of the different transmission routes of the SARS-CoV-2 virus is an urgent research priority. To that end, the different transmission routes and their role in determining the evolution of the Covid-19 pandemic are analyzed in this work. The probability of infection caused by inhaling virus-laden droplets (initial ejection diameters between 0.5
Language	English
Publishing date	2020-11-28
Publishing country	United States
Document type	Journal Article
ZDB-ID	1472743-2
ISSN	1089-7666 ; 1070-6631
ISSN (online)	1089-7666
ISSN	1070-6631
DOI	10.1063/5.0034032
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Article: An opinion on the multiscale nature of Covid-19 type disease spread

Chaudhuri, Swetaprovo / Saha, Abhishek / Basu, Saptarshi

Current opinion in colloid & interface science. 2021 Aug., v. 54

2021

Abstract	Recognizing the multiscale, interdisciplinary nature of the Covid-19 transmission dynamics, we discuss some recent developments concerning an attempt to construct a disease spread model from the flow physics of infectious droplets and aerosols and the frequency of contact between susceptible individuals with the infectious aerosol cloud. Such an approach begins with the exhalation event–specific, respiratory droplet size distribution (both airborne/aerosolized and ballistic droplets), followed by tracking its evolution in the exhaled air to estimate the probability of infection and the rate constants of the disease spread model. The basic formulations and structure of submodels, experiments involved to validate those submodels, are discussed. Finally, in the context of preventive measures, respiratory droplet–face mask interactions are described.
Keywords	COVID-19 infection ; aerosols ; air ; breathing ; droplet size ; models ; probability
Language	English
Dates of publication	2021-08
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	2019683-0
ISSN	1359-0294
ISSN	1359-0294
DOI	10.1016/j.cocis.2021.101462
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Analysing the distribution of SARS-CoV-2 infections in schools: integrating model predictions with real world observations

Mukherjee, Arnab / Mishra, Sharmistha / Kumar Murty, Vijaya / Chaudhuri, Swetaprovo

bioRxiv

Abstract: School closures were used as strategies to mitigate transmission in the COVID-19 pandemic. Understanding the nature of SARS-CoV-2 outbreaks and the distribution of infections in classrooms could help inform targeted or `precision9 preventive measures and ...

Abstract	School closures were used as strategies to mitigate transmission in the COVID-19 pandemic. Understanding the nature of SARS-CoV-2 outbreaks and the distribution of infections in classrooms could help inform targeted or `precision9 preventive measures and outbreak management in schools, in response to future pandemics. In this work, we derive an analytical model of Probability Density Function (PDF) of SARS-CoV-2 secondary infections and compare the model with infection data from all public schools in Ontario, Canada between September-December, 2021. The model accounts for major sources of variability in airborne transmission like viral load and dose-response (i.e., the human body9s response to pathogen exposure), air change rate, room dimension, and classroom occupancy. Comparisons between reported cases and the modeled PDF demonstrated the intrinsic overdispersed nature of the real-world and modeled distributions, but uncovered deviations stemming from an assumption of homogeneous spread within a classroom. The inclusion of near-field transmission effects resolved the discrepancy with improved quantitative agreement between the data and modeled distributions. This study provides a practical tool for predicting the size of outbreaks from one index infection, in closed spaces such as schools, and could be applied to inform more focused mitigation measures.
Keywords	covid19
Language	English
Publishing date	2023-12-21
Publisher	Cold Spring Harbor Laboratory
Document type	Article ; Online
DOI	10.1101/2023.12.21.572736
Database	COVID19

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Article: Insights on drying and precipitation dynamics of respiratory droplets from the perspective of COVID-19.

Basu, Saptarshi / Kabi, Prasenjit / Chaudhuri, Swetaprovo / Saha, Abhishek

Physics of fluids (Woodbury, N.Y. : 1994)

2020 Volume 32, Issue 12, Page(s) 123317

Abstract: We isolate a nano-colloidal droplet of surrogate mucosalivary fluid to gain fundamental insights into airborne nuclei's infectivity and viral load distribution during the COVID-19 pandemic. The salt-water solution containing particles at reported viral ... ...

Abstract	We isolate a nano-colloidal droplet of surrogate mucosalivary fluid to gain fundamental insights into airborne nuclei's infectivity and viral load distribution during the COVID-19 pandemic. The salt-water solution containing particles at reported viral loads is acoustically trapped in a contactless environment to emulate the drying, flow, and precipitation dynamics of real airborne droplets. Similar experiments validate observations with the surrogate fluid with samples of human saliva samples from a healthy subject. A unique feature emerges regarding the final crystallite dimension; it is always 20%-30% of the initial droplet diameter for different sizes and ambient conditions. Airborne-precipitates nearly enclose the viral load within its bulk while the substrate precipitates exhibit a high percentage (∼80-90%) of exposed virions (depending on the surface). This work demonstrates the leveraging of an inert nano-colloidal system to gain insights into an equivalent biological system.
Language	English
Publishing date	2020-12-29
Publishing country	United States
Document type	Journal Article
ZDB-ID	1472743-2
ISSN	1089-7666 ; 1070-6631
ISSN (online)	1089-7666
ISSN	1070-6631
DOI	10.1063/5.0037360
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Article ; Online: On secondary atomization and blockage of surrogate cough droplets in single- and multilayer face masks.

Sharma, Shubham / Pinto, Roven / Saha, Abhishek / Chaudhuri, Swetaprovo / Basu, Saptarshi

Science advances

2021 Volume 7, Issue 10

Abstract: Face masks prevent transmission of infectious respiratory diseases by blocking large droplets and aerosols during exhalation or inhalation. While three-layer masks are generally advised, many commonly available or makeshift masks contain single or double ...

Abstract	Face masks prevent transmission of infectious respiratory diseases by blocking large droplets and aerosols during exhalation or inhalation. While three-layer masks are generally advised, many commonly available or makeshift masks contain single or double layers. Using carefully designed experiments involving high-speed imaging along with physics-based analysis, we show that high-momentum, large-sized (>250 micrometer) surrogate cough droplets can penetrate single- or double-layer mask material to a significant extent. The penetrated droplets can atomize into numerous much smaller (<100 micrometer) droplets, which could remain airborne for a significant time. The possibility of secondary atomization of high-momentum cough droplets by hydrodynamic focusing and extrusion through the microscale pores in the fibrous network of the single/double-layer mask material needs to be considered in determining mask efficacy. Three-layer masks can effectively block these droplets and thus could be ubiquitously used as a key tool against COVID-19 or similar respiratory diseases.
MeSH term(s)	Aerosols ; COVID-19/diagnosis ; COVID-19/virology ; Cough/pathology ; Humans ; Image Processing, Computer-Assisted ; Masks ; Particle Size ; Probability ; SARS-CoV-2/physiology ; Viral Load
Chemical Substances	Aerosols
Language	English
Publishing date	2021-03-05
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2810933-8
ISSN	2375-2548 ; 2375-2548
ISSN (online)	2375-2548
ISSN	2375-2548
DOI	10.1126/sciadv.abf0452
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Article: Two-dimensional mathematical framework for evaporation dynamics of respiratory droplets.

Majee, Sreeparna / Saha, Abhishek / Chaudhuri, Swetaprovo / Chakravortty, Dipshikha / Basu, Saptarshi

Physics of fluids (Woodbury, N.Y. : 1994)

2021 Volume 33, Issue 10, Page(s) 103302

Abstract: In majority of pandemics in human history, respiratory bio-aerosol is the most common route of transmission of diseases. These tiny droplets ejected through mouth and nose from an infected person during exhalation process like coughing, sneezing, ... ...

Abstract	In majority of pandemics in human history, respiratory bio-aerosol is the most common route of transmission of diseases. These tiny droplets ejected through mouth and nose from an infected person during exhalation process like coughing, sneezing, speaking, and breathing consist of pathogens and a complex mixture of volatile and nonvolatile substances. A cloud of droplets ejected in such an event gets transmitted in the air, causing a series of coupled thermo-physical processes. Contemplating an individual airborne droplet in the cloud, boundary layers and wakes develop due to relative motion between the droplet and the ambient air. The complex phenomenon of the droplet's dynamics, such as shear-driven internal circulation of the liquid phase and Stefan flow due to vaporization or condensation, comes into effect. In this study, we present a mathematical description of the coupled subprocesses, including droplet aerodynamics, heat, and mass transfer, which were identified and subsequently solved. The presented two-dimensional model gives a complete analysis encompassing the gas phase coupled with the liquid phase responsible for the airborne droplet kinetics in the ambient environment. The transient inhomogeneity of temperature and concentration distribution in the liquid phase caused due to the convective and diffusive transports are captured in the 2D model. The evaporation time and distance traveled by droplets prior to nuclei or aerosol formation are computed for major geographical locations around the globe for nominal-windy conditions. The model presented can be used for determining the evaporation timescale of any viral or bacterial laden respiratory droplets across any geographical location.
Language	English
Publishing date	2021-10-01
Publishing country	United States
Document type	Journal Article
ZDB-ID	1472743-2
ISSN	1089-7666 ; 1070-6631
ISSN (online)	1089-7666
ISSN	1070-6631
DOI	10.1063/5.0064635
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Article ; Online: Investigating thermoacoustic instability mitigation dynamics with a Kuramoto model for flamelet oscillators.

Dutta, Ankit Kumar / Ramachandran, Gopakumar / Chaudhuri, Swetaprovo

Physical review. E

2019 Volume 99, Issue 3-1, Page(s) 32215

Abstract: In this paper, we present experimental observations and phenomenological modeling of the intermittent dynamics that emerge while mitigating thermoacoustic instability by rotating the otherwise static swirler in a lean premixed, laboratory-scale combustor. ...

Abstract	In this paper, we present experimental observations and phenomenological modeling of the intermittent dynamics that emerge while mitigating thermoacoustic instability by rotating the otherwise static swirler in a lean premixed, laboratory-scale combustor. Starting with a self-excited thermoacoustically unstable combustor, here we find that a progressive increase in swirler rotation rate does not uniformly decrease amplitudes of coherent, sinusoidal pressure or heat-release-rate oscillations. Instead, these oscillations emerge as high-amplitude bursts separated by low-amplitude noise in the signal. At increased rotational speeds, the high-amplitude coherent oscillations become scarce and their duration in the signal reduces. The velocity field from high-speed particle image velocimetry and simultaneous pressure and chemiluminescence data support these observations. Such an intermittent route to instability mitigation is reminiscent of the opposite transition implemented by changing the Reynolds number from a fully chaotic state to a fully unstable state. To model such dynamics phenomenologically, we discretize the swirling turbulent premixed flame into an ensemble of flamelet oscillators arranged circumferentially around the center body of the swirler. The Kuramoto model is proposed for these flamelet oscillators which is subsequently used to analyze their synchronization dynamics. The order parameter r, which is a measure of the synchronization between the oscillator phases, provides critical insights on the transition from the thermoacoustically unstable to stable states via intermittency. Finally, it is shown that the Kuramoto model for flamelet oscillator can qualitatively reproduce the time-averaged and intermittent dynamics while transitioning from the state of thermoacoustic instability to a state of incoherent noisy oscillations.
Language	English
Publishing date	2019-04-11
Publishing country	United States
Document type	Journal Article
ZDB-ID	2844562-4
ISSN	2470-0053 ; 2470-0045
ISSN (online)	2470-0053
ISSN	2470-0045
DOI	10.1103/PhysRevE.99.032215
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