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Sombuddha Bagchi

Bio: Sombuddha Bagchi is an academic researcher from Jadavpur University. The author has contributed to research in topics: Physics & Statistical physics. The author has an hindex of 1, co-authored 3 publications receiving 3 citations.

Papers
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Book ChapterDOI
04 Jan 2018
TL;DR: In this paper, an unstructured grid finite volume method was used and simulations were carried out to simulate a two-dimensional laminar transient flow past a cylindrical bluff body.
Abstract: A two-dimensional, laminar transient flow past a cylindrical bluff body, with methane injection perpendicular to the direction of the free stream flow, i.e. the cross-flow arrangement, is numerically studied. An unstructured grid finite volume method is used and simulations were carried out. The methane mass fraction and the injection velocity of methane injected from the slotted cylinder are altered simultaneously, and their effects on the combustion, flame characteristics, and fluid mechanics are investigated. The flame is anchored right in front of the cylinder and is stabilized by the wake of the bluff body. The current investigation illustrates the qualitative aspects of the vortex shedding phenomena. A particular case of injection velocity and mass fraction is studied in detail and its vortex shedding phenomena are analysed minutely. The non-reacting flow exhibits 2P mode of vortex shedding while the reacting flow exhibits the more common 2S mode. Fast Fourier transform analysis of the temporally fluctuating lift coefficient is performed for the different cases carried out in the present study.

3 citations

Book ChapterDOI
01 Jan 2020
TL;DR: In this paper, the authors present a brief review of the recent developments on flow past a bluff body in both non-reacting and reacting flow situations, and highlight the distinctive dynamics of flow past the bluff body when another fluid is injected from the body itself.
Abstract: The unsteady fluid flow past a bluff body has been widely studied, particularly due to the distinctive flow features observed in the wake of the bluff body itself. The inherently complex nature of the problem has promoted several investigations over the past few decades. Apart from the non-reacting situation, bluff bodies have also been used in reacting flows as flame holders in various practical combustors. Recently, some researchers have reported practical scenarios where a different fluid is injected from ports on the bluff body on to the free stream, and there exist a few studies on the dynamics of such a flow scenario in both the non-reacting and reacting cases. The present chapter presents a brief review of the recent developments on flow past a bluff body in the non-reacting and reacting flow situations. The chapter also highlights the distinctive dynamics of flow past a bluff body when another fluid is injected from the bluff body itself. The effectiveness of the proper orthogonal decomposition technique to analyze the dynamics of flows past bluff bodies is also highlighted.
Proceedings ArticleDOI
03 Jan 2022
TL;DR: In this paper , the authors investigate the dynamical characteristics corresponding to the structural fluctuations of a cantilever suspended in a turbulent flow and explore the ability of network analysis to identify the different dynamical states and probe the viability of using quantifiers of network topology as precursors for the onset of aeroelastic flutter.
Abstract: We investigate the dynamical characteristics corresponding to the structural fluctuations of a cantilever suspended in a turbulent flow. First, we explore the ability of network analysis to identify the different dynamical states and probe the viability of using quantifiers of network topology as precursors for the onset of aeroelastic flutter. By increasing the flow rate or Reynolds number of the jet quasi-steadily, we observe that the structural oscillations, measured using a strain gauge, transition from low amplitude chaotic oscillations to periodic large amplitude oscillations associated with flutter. We characterize the dynamical states of the system for all these Reynold numbers by constructing the weighted correlation network (CN) from the time series of strain and identifying the network properties which can be used as precursors for the onset of aeroelastic flutter. Furthermore, we illustrate the evolution of mutual statistical influence between the structural oscillations and the flow field by using Pearson correlation. We use this information in conjunction with Granger causality to identify the causal dependence between the structural oscillations and velocity fluctuations. We identify the causal variable during each dynamical regime at different regions of the flow field. Therefore, we illustrate the directional dependence through a `cause-effect' relationship in this flow-structure interaction as it transitions to an aeroelastic flutter.
Book ChapterDOI
04 Jan 2018
TL;DR: A numerical simulation has been performed to obtain the velocity profile for a non-standard aerofoil over five angles-of-attack (AoAs) including negative ones which have been validated against the data obtained from wind tunnel experimentation for conditions compatible with the simulation.
Abstract: Aerofoils have been used comprehensively in the research and development of aerodynamic equipment and machineries. Implementation of computational fluid dynamics (CFD) for study of aerofoils for numerous conditions has been on the rise. Despite the reduction in cost and efforts, the simulation data still differ considerably from the real-life data as a result of several assumptions taken in numerical simulations. Henceforth, validation against experimental data is of utmost importance. Furthermore, determination of numerical and experimental data for new aerofoil sections has been a necessity as the use of such sections may enhance the aerodynamic properties of various vehicles and instruments. In this paper, a numerical simulation has been performed to obtain the velocity profile for a non-standard aerofoil over five angles-of-attack (AoAs) including negative ones which have been validated against the data obtained from wind tunnel experimentation for conditions compatible with the simulation. The contemporary results obtained show commendable convergence.
Journal ArticleDOI
TL;DR: In this paper, the authors investigate the dynamic characteristics corresponding to the structural fluctuations of a cantilever suspended in a turbulent flow and explore the ability of network analysis to identify the different dynamic states and probe the viability of using quantifiers of network topology as precursors for the onset of limit cycle oscillations.
Abstract: We investigate the dynamic characteristics corresponding to the structural fluctuations of a cantilever suspended in a turbulent flow. To investigate the intricate dynamics of the flow–structure interaction, first, we explore the ability of network analysis to identify the different dynamic states and probe the viability of using quantifiers of network topology as precursors for the onset of limit-cycle oscillations. By increasing the Reynolds number, we observe that the structural oscillations, measured using a strain gauge, transition from low-amplitude chaotic oscillations to large-amplitude periodic oscillations associated with limit-cycle oscillations. We characterize the dynamic states of the system by constructing the weighted correlation network from the time series of strain and identifying the network properties that have the potential to be used as precursors for the onset of limit-cycle oscillations. Furthermore, we use Pearson correlation to illustrate the evolution of mutual statistical influence between the structural oscillations and the flowfield. We use this information and the Granger causality to identify the causal dependence between the structural oscillations and velocity fluctuations. By identifying the causal variable during each regime, we illustrate the directional dependence through a cause–effect relationship in this flow–structure interaction as it transitions to limit-cycle oscillations.

Cited by
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01 Nov 2004
TL;DR: In this article, the authors analyze the local flame extinction and reignition of a counterflow diffusion flame perturbed by a laminar vortex ring, and the temporal evolution of the mixing layer is determined using the classical mixture fraction approach, with both unsteady and curvature effects taken into account.
Abstract: We analyze the local flame extinction and reignition of a counterflow diffusion flame perturbed by a laminar vortex ring. Local flame extinction leads to the appearance of flame edges separating the burning and extinguished regions of the distorted mixing layer. The dynamics of these edges is modeled based on previous numerical results, with heat release effects fully taken into account, which provide the propagation velocity of triple and edge flames in terms of the upstream unperturbed value of the scalar dissipation. The temporal evolution of the mixing layer is determined using the classical mixture fraction approach, with both unsteady and curvature effects taken into account. Although variable density effects play an important role in exothermic reacting mixing layers, in this paper the description of the mixing layer is carried out using the constant density approximation, leading to a simplified analytical description of the flow field. The mathematical model reveals the relevant nondimensional parameters governing diffusion-flame/vortex interactions and provides the parameter range for the more relevant regime of local flame extinction followed by reignition via flame edges. Despite the simplicity of the model, the results show very good agreement with previously published experimental results.

18 citations

Book ChapterDOI
01 Jan 2020
TL;DR: In this paper, the authors present a brief review of the recent developments on flow past a bluff body in both non-reacting and reacting flow situations, and highlight the distinctive dynamics of flow past the bluff body when another fluid is injected from the body itself.
Abstract: The unsteady fluid flow past a bluff body has been widely studied, particularly due to the distinctive flow features observed in the wake of the bluff body itself. The inherently complex nature of the problem has promoted several investigations over the past few decades. Apart from the non-reacting situation, bluff bodies have also been used in reacting flows as flame holders in various practical combustors. Recently, some researchers have reported practical scenarios where a different fluid is injected from ports on the bluff body on to the free stream, and there exist a few studies on the dynamics of such a flow scenario in both the non-reacting and reacting cases. The present chapter presents a brief review of the recent developments on flow past a bluff body in the non-reacting and reacting flow situations. The chapter also highlights the distinctive dynamics of flow past a bluff body when another fluid is injected from the bluff body itself. The effectiveness of the proper orthogonal decomposition technique to analyze the dynamics of flows past bluff bodies is also highlighted.
01 Jan 1986
TL;DR: In this paper, a theoretical model of a laminar diffusion flame at the leading edge of a fuel plate in a forced convective flow is presented and solved numerically to study the flame stabilization and blowoff phenomena.
Abstract: Abstract A theoretical model of a laminar diffusion flame at the leading edge of a fuel plate in a forced convective flow is presented and solved numerically to study the flame stabilization and blowoff phenomena. The system of governing equations consists of the two-dimensional Navier-Stokes momentum, energy and species equations with a one-step overall chemical reaction and second-order, finite rate Arrhenius kinetics. The computation is performed over a wide range of Damkohler numbers. For large Damkohler numbers, envelope flames are found to exist where the computed fuel evaporation rate, the flame stand-off distance and the velocity profiles show certain similitude. As the Damkohler number is lowered, a transition to open-tip flame takes place where the flame becomes stabilized on the sides of the fuel plate. Further decreasing of the Damkohler number pushes the diffusion flame downstream out of the leading edge region. In this paper, the flame structures of the envelope and the open-tip flames are p...