Chandan Bose

The University of Edinburgh | UoE · School of Engineering

The present study investigates the complex vortex interactions in two-dimensional flow-field behind a symmetric NACA0012 airfoil undergoing a prescribed periodic pitching-plunging motion in low Reynolds number regime. The flow-field transitions from periodic to chaotic through a quasi-periodic route as the plunge amplitude is gradually increased. T...

This study investigates the transitional wake dynamics of a simultaneously pitching-heaving airfoil in the low Reynolds number regime. The transition from K\'arm\'an to reverse K\'arm\'an wakes and the subsequent wake deflection are known to take place entirely in the periodic regime as the dynamic heave velocity $\kappa h$ (proportionally, the amp...

The present study focuses on investigating the bifurcation characteristics of a pitch–plunge aeroelastic system possessing coupled non-smooth nonlinearities, both in structural and aerodynamic fronts. To this end, a freeplay nonlinearity is considered in the stiffness of the pitch degree-of-freedom. The effects of dynamic stall arising due to large...

This study focuses on characterizing the bifurcation scenario and the underlying synchrony behavior in a nonlinear aeroelastic system under deterministic as well as stochastic inflow conditions. Wind tunnel experiments are carried out for a canonical pitch-plunge aeroelastic system subjected to dynamic stall conditions. The system is observed to un...

The effect of a chordwise flexible aft-tail of a rigid heaving aerofoil on the dynamical transitions of the trailing-wake is studied here. The two-way coupled fluid-solid dynamics is simulated using an in-house fluid-structure interaction (FSI) platform, comprising a discrete forcing immersed boundary method based incompressible Navier–Stokes solve...

This study investigates the suppression mechanism of instabilities induced by fluid-structure interactions (FSI) using passive vibration absorption devices, such as nonlinear energy sink (NES). The present FSI framework comprises a low-order phenomenological model, wherein the wake effect is modeled using the classical Van der Pol oscillator. The s...

View Video Presentation: https://doi.org/10.2514/6.2022-4138.vid An integral boundary-layer formulation is used to dynamically detect the occurrence of boundary-layer detachment if any, and its location on the airfoil surface. Weak separation or ‘boundary-layer thickening’ is modeled through viscous-inviscid interaction between the boundary-layer f...

The present study focuses on identifying dynamical transition boundaries and presents an order-to-chaos map for the unsteady flow field of a flapping foil in the low Reynolds number regime. The effect of an extensive parametric space, covering a large number of kinematic conditions, has been investigated. It is shown that the conventional non-dimen...

This study focuses on characterising the bifurcation scenario and the underlying synchrony behaviour in a nonlinear aeroelastic system under deterministic as well as stochastic inflow conditions. Wind tunnel experiments are carried out for a canonical pitch-plunge aeroelastic system subjected to dynamic stall conditions. The system is observed to u...

This study focuses on characterizing the fatigue damage accumulated in nonlinear aeroelastic systems subjected to stochastic inflows through both numerical simulations and wind tunnel experiments. In the mathematical model, nonlinearities are assumed to exist either in the structure (via a cubic hardening nonlinearity in the pitch stiffness), or in...

The present study focuses on investigating the bifurcation characteristics of a pitch-plunge aeroelastic system possessing coupled non-smooth nonlinearities, both in structural and aerodynamic fronts. To this end, a freeplay nonlinearity is considered in the stiffness of the pitch degree-of-freedom (DoF). The effects of dynamic stall arising due to...

An elastically-supported bluff body structure experiences high-amplitude vortex-induced vibrations (VIV) due to the coupled fluid-structure interactions (FSI) in the presence of oncoming flow. This study investigates the suppression mechanism of these FSI-induced instabilities using a passive vibration absorption device-nonlinear energy sink (NES)....

The corresponding article can be read at https://doi.org/10.2514/6.2022-1969.

This paper investigates the underlying flow physics of static stall on a finite wing in the presence of bio-inspired leading-edge protuberances (LEPs) at a Reynolds number of 6×10^4. We present Unsteady Reynolds Average Navier-Stokes (URANS) flow simulations of the static stall behavior of a three-dimensional wing (spanning from wall to wall) with...

This study focuses on characterizing the fatigue damage accumulated in nonlinear aeroelastic systems subjected to stochastic inflows through both numerical simulations and wind tunnel experiments. In the mathematical model, nonlinearities are assumed to exist either in the structure (via a cubic hardening nonlinearity in the pitch stiffness), or in...

This study investigates the dynamical behaviour of the flapping filament subjected to a uniform inlet velocity at a low Reynolds number, considering the heaving amplitude as a bifurcation parameter. A discrete forcing immersed boundary method (IBM)-based in-house fluid-structure interaction (FSI) solver is used for the present simulations. The flap...

Dynamic stall is a subject of continued interest in the aerodynamics and aeroelasticity communities due to its broad range of engineering and biological applications, such as helicopter rotor blades, rapidly maneuvering flight, wind turbines, jet engine compressor blades, or flapping of insect wings. This study focuses on investigating the unsteady...

The primary motivation behind this study comes from the need for developing innovative engineering systems to harvest ambient wind energy from different classes of flow-induced vibrations. This study deals with the piezoelectric energy harvesting from the flow-induced vibration of a bluff-body with two symmetric splitters of varying lengths install...

Vortex-Induced Vibration (VIV) is often modelled as a two-way-coupled phenomenon wherein the structure and the wake behave as two interacting oscillators. In this chapter, we analyse the coupled interactions between these two oscillators from the purview of synchronization theory. To that end, a low-order wake oscillator model comprising of a class...

This chapter focuses on investigating the response characteristics of a coupled non-smooth nonlinear aeroelastic system subjected to randomly fluctuating inflow. The non-smoothness in the structure can be attributed to freeplay nonlinearity, and the aerodynamic loads are dictated by dynamic stall condition. Stochastic inflow gives rise to noise-ind...

This study reports that the choice of a seemingly appropriate linear algebra solver may fail to arrive at the accurate unsteady flow-field solution, leading to non-physical results. To that end, we take up a well-studied canonical problem of a periodically pitching airfoil in uniform free-stream condition. Simulations are performed in the low Reyno...

Water entry/exit and water impact are found in a broad range of applications, starting from the biological propulsion of a jumping fish to various offshore Engineering problems. Aquatic jumpers exhibit complicated dynamics in order to produce the required thrust during the transition from water to air due to the change in the medium density. On the...

The present study aims to investigate the synchronization characteristics of a pitch-plunge aeroelastic system subjected to coupled structural free-play and dynamic stall-induced aerodynamic nonlinearities. The semi-empirical Leishman-Beddoes (LB) aerodynamic model is used to capture the dynamic stall phenomena at large angles-of-attack (AoA). A bi...

Ambient energy harvesting from the vortex-induced vibration of circular cylinders has been extensively studied in recent years. However, the effect of multiple splitters attached to the cylinder surface in different configurations on the energy harvesting performance is not well understood to date. This study is focused on enhancing the piezoelectr...

This study is focused on investigating hybrid piezoelectric energy harvesting from the flow-induced vibration of a circular cylinder by using two symmetric splitters in different relative angular positions with respect to the oncoming uniform flow. Wind tunnel experiments and numerical simulations are carried out to study the effect of different an...

This paper investigates theBose, Chandan transitional flow dynamics behind a passively flapping airfoil supported by nonlinear springs in the presence of gusty inflow.Gupta, Sayan The fluid-structure interaction (FSI) framework is composed of an incompressible Navier-Stokes solver weakly coupled with a two degree-of-freedom (dof) nonlinear structur...

This study investigates the three-dimensional flow dynamics of a low-aspect-ratio flapping wing at a Reynolds number of 250. A discrete immersed boundary method is employed to solve the three-dimensional Navier-Stokes equation. Kinematic parameters, particularly the amplitude and frequency of the flapping motion, are found to have significant effec...

The present work explores the role of phase-difference on the transitional flow dynamics of a pitching-plunging foil. An extensive parameter space of plunge amplitude (h) and phase offset (ϕ) between pitch-plunge motions is considered keeping the pitch amplitude and non-dimensional flapping frequency constant (α=15o & k=4). Numerical simulations ar...

The present study attempts to capture the fluid-structure interaction dynamics of a chord-wise flexible flapping wing system using a limited mode structural model coupled with a high-fidelity Navier-Stokes solver. The wing is modeled as two elliptic rigid foils connected by a non-linear torsional spring that incorporates the chord-wise bending stif...

The present work focuses on investigating the underlying flow physics behind the transition from periodicity to aperiodicity in the flow past a harmonically plunging elliptic foil as the plunge amplitude is increased to a high value. Two-dimensional (2D) numerical simulations have been performed in the low Reynolds number regime using an in-house f...

The present paper aims to gain an understanding of the physics associated with the fluid-structure interaction behavior of a flexible filament interacting with the wake of an upstream rigid cylinder situated at a finite distance. The computational framework of the present high fidelity numerical simulations consist of an incompressible Navier-Stoke...

The effect of stochastic inflow fluctuations on the jet-switching characteristics of a harmonically plunging elliptic foil at a low Reynolds number regime has been analysed in the present study. The inflow fluctuations are generated by simulating an Ornstein-Uhlenbeck process - a stationary Gauss-Markov process - with a chosen correlation function....

The present study focuses on formulating a fluid–structure interaction (FSI) framework by coupling a finite element analysis (FEA) based structural solver and a lumped vortex method (LVM) based potential flow solver to study the coupled dynamics involved in the undulatory and oscillatory swimming of fishes. The caudal fin of a carangiform fish is m...

The present paper numerically investigates the aerodynamic characteristics of a chord-wise flexible filament-like structure subjected to a fluctuating inflow in terms of the wake of a rigid cylinder situated upstream in the low Reynolds number regime (RED = 500, where D is the diameter of the cylinder). The numerical simulations are performed with...

The present work focuses on investigating the underlying flow physics behind the transition from periodicity to aperiodicity in the flow past a harmonically plunging elliptic foil as the plunge amplitude is increased to a high value. Two-dimensional (2D) numerical simulations have been performed in the low Reynolds number regime using an in-house f...

The present paper aims to gain an understanding of the physics associated with the fluid-structure interaction behavior of a flex- ible filament interacting with the wake of an upstream rigid cylinder sit- uated at a finite distance. The computational framework of the present high fidelity numerical simulations consist of an incompressible Navier-...

The present work is focused on investigating the effect of noisy input fluctuations on a harmonically plunging elliptic foil in the low Reynolds number regime (Re=300). Simulations are carried out using a discrete forcing Immersed Boundary Method (IBM) based in-house Navier-Stokes solver. The stochastic noisy inlet velocity is modeled as the Ornste...

This paper focuses on investigating the aerodynamic load generation of rigid and flexible wings undergoing asymmetric flapping motion through wind tunnel experiments in uniform inflow condition. The aerodynamic forces of the designed flapping wing setup are measured through a 6-dof force/torque sensor. A rigid wing and two different flexible membra...

This study focuses on numerically analyzing the transition from periodic to chaotic dynamics in the fluid-elastic response of a 2-dof flexibly-mounted airfoil with chord-wise rigidity. The computational framework is composed of a high fidelity Navier–Stokes solver, weakly coupled with a structural model having geometric nonlinearity represented by...

This study investigates the transitional flow dynamics in the wake of a pitching-plunging airfoil in the low Reynolds number regime. In the periodic regime, the transition from Karman to reverse Karman vortex-streets and the subsequent wake deflection with a gradual increase in the amplitude based Strouhal number (St) are well investigated in the l...

This study focuses on numerically analyzing the transition from periodic to chaotic dy- namics in the fluid-elastic response of a 2-dof spring-mounted airfoil, which models the behavior of a chord-wise rigid wing with span-wise flexibility. The computational framework is composed of a high fidelity Navier-Stokes solver, weakly coupled with a struct...

This study deals with energy harvesting from vortex-induced vibration (VIV) of a flexible cantilever plate placed in the wake of a rigid cylinder. Conventionally, the plate is designed to resonate with the vortex shedding frequency behind the cylinder at a given flow velocity. The experimental results presented here show that the frequency of the p...

The present paper is focused on understanding the fluid-structure interaction (FSI) behavior associated with the flow-induced vibrations of a chordwise flexible filament subjected to perturbed flows. The perturbed flow-field is generated in terms of the wake of a rigidly held cylinder situated upstream in the presence of a steady uniform free-strea...

The present paper investigates the effects of noisy flow fluctuations on the fluid-structure interaction (FSI) behaviour of a span-wise flexible wing modelled as a two degree-of-freedom elastically mounted flapping airfoil. In the sterile flow conditions, the system undergoes a Hopf bifurcation as the free-stream velocity exceeds a critical limit r...

The present study focuses on formulating an FSI framework by coupling a Finite Element Analysis (FEA) based structural solver and a Lumped Vortex Method (LVM) based potential flow solver, to study the coupled dynamics involved in the undulatory and oscillatory swimming of fishes. The caudal fin of a carangiform fish is modelled as a continuous cant...

Research into the design and development of bio-inspired futuristic devices like Micro Aerial Vehicles (MAVs) or Autonomous Underwater Vehicles (AUVs) have recently gained an impetus due to the necessity for the development of futuristic surveillance tools. The inspiration for the design of MAVs/AUVs comes from the natural bio-propulsion systems li...

This study investigates energy harvesting from vortex induced vibrations of a flexible cantilevered flapper placed in the wake of a rigid circular cylinder. The effect of the gap between the cylinder and the flapper on the energy harvested is investigated through wind tunnel experiments and numerical simulations. As the flow speed is varied, a tran...

This paper deals with the nonlinear fluid structure interaction (FSI) dynamics of a dipteran flight motor inspired flapping system in an inviscid fluid. In the present study, the FSI effects are incorporated to an existing forced Duffing oscillator model to gain a clear understanding of the nonlinear dynamical behaviour of the system in the presenc...

The present paper investigates the effects of noisy flow fluctuations on the fluid-structure interaction (FSI) behaviour of a span-wise flexible wing modelled as a two degree-of-freedom elastically mounted flapping airfoil. In the sterile flow conditions, the system undergoes a Hopf bifurcation as the free-stream velocity exceeds a critical limit r...

Chaotic wake patterns in the flow past flapping airfoils have been reported earlier for high plunge velocities. The present work focuses on analysing the dynamics and identifying the route to chaos in this phenomenon. The unsteady flow-field is investigated using an incompressible Navier-Stokes solver. A bifurcation analysis with the plunge amplitu...

The transition in the flow-periodicity behind an airfoil oscillating with prescribed si- nusoidal pitching-plunging motion has been explored by proper orthogonal decomposition (POD) technique. The high fidelity simulation of the viscous flow past a flapping airfoil has been performed by a finite volume based incompressible Navier-Stokes solver. The...

The present study investigates the flow physics over an elastically mounted symmetric NACA 0012 airfoil with bending and torsion flexibility in the low Reynolds number regime. The dynamical behaviour of the span-wise flexible wing is studied at a comparable struc- tural and fluid added mass to the system (solid to fluid added mass ratio, μ = 5) fit...

This study deals with energy harvesting from vortex induced vibration (VIV) of a flexible cantilever plate placed in the wake of a rigid cylinder. Conventionally, the plate is designed to resonate with the vortex shedding frequency behind the cylinder at a given flow velocity. The experimental results presented here show that the frequency of the p...

This paper investigates the transition in the flow dynamics past a flapping wing in low Reynolds number regime through recurrence plots (RP) and recurrence quantification analysis (RQA). Recently, the unsteady aerodynamics of flapping wings at low Reynolds number has been receiving substantial attention in relation to the efficient design of biolog...

This paper investigates the role of chord-wise flexibility in the propulsive performance and the fluid structure interaction (FSI) dynamics of a flapping fin modelled as a chord-wise flexible cantilever beam with a sinusoidal support motion in an inviscid fluid. Finite element analyses and lumped vortex method have been employed to build the presen...

In this paper, the nonlinear fluid-structure interaction (FSI) dynamics of a dipteran flight motor has been explored in an inviscid fluid by nonlinear dynamics techniques. The flexible insect flight-motor has been modeled as a forced Duffing oscillator to predict the kinematics of an insect wing in the presence of aerodynamic loads. The nonlinear s...

The dynamics of a flexible flapping wing is investigated by modelling it as a coupled nonlinear fluid-structure interaction (FSI) system in the low Reynolds number flow regime in accordance to the flight of flapping wing micro air vehicles (MAVs). A bifurcation analysis, by varying the free-stream wind velocity (U ∞) as the control parameter, revea...

Numerical simulations of flow over a flapping wing with pitch and plunge kinematics have been carried out in two dimensions in this paper by a finite volume based incompressible Navier-Stokes solver using parallel computing. The present study aims to understand the unsteady aerodynamics of the pitching-plunging motion of a NACA0012 airfoil by inves...