Papers by Promode R Bandyopadhyay
Journal of Fluids Engineering-transactions of The Asme, Mar 1, 1997
The understanding of fish maneuvering and its application to underwater rigid bodies are consider... more The understanding of fish maneuvering and its application to underwater rigid bodies are considered. The goal is to gain insight into stealth. The recent progress made in NUWC is reviewed. Fish morphology suggests that control fins for maneuverability have unique scalar relationships irrespective of their speed type. Maneuvering experiments are carried out with fish that are fast yet maneuverable. The gap in maneuverability between fish and small underwater vehicles is quantified. The hydrodynamics of a dorsal fin based brisk maneuvering device and a dual flapping foil device, as applied to rigid cylindrical bodies, are described. The role of pectoral wings in maneuvering and station keeping near surface waves is discussed. A pendulum model of dolphin swimming is presented to show that body length and tail flapping frequency are related. For nearly neutrally buoyant bodies, Froude number and maneuverability are related. Analysis of measurements indicates that the Strouhal number of dolphins is a constant. The mechanism of discrete and deterministic vortex shedding from oscillating control surfaces has the property of large amplitude unsteady forcing and an exquisite phase dependence, which makes it inherently amenable to active control for precision maneuvering. Theoretical control studies are carried out to demonstrate the feasibility of maneuverability of biologically inspired bodies under surface waves. The application of fish hydrodynamics to the silencing of propulsors is considered. Two strategies for the reduction of radiated noise are developed. The effects of a reduction of rotational rate are modeled. The active cambering of blades made of digitally programmable artificial muscles, and their thrust enhancement, are demonstrated. Next, wake momentum filling is carried out by artificial muscles at the trailing edge of a stator blade of an upstream stator propulsor, and articulating them like a fish tail. A reduction of radiated noise, called blade tonals, is demonstrated theoretically. FIG. 1. Definition of length scales of a fish. FIG. 2. Morphology of dorsal fins of fish families.
Scientific Reports
When a sailfish circles to corral a school of flying fish in a vortex near the ocean surface, a t... more When a sailfish circles to corral a school of flying fish in a vortex near the ocean surface, a tiny patch of arced surface waves confined to oppositely placed 70° sectors appears dispersing coherently, but why? It is modeled that, when the fish motions stop suddenly, the corralled school compacts, the tail shed propulsion vortices touch, break and radiate the pressure released from the centrifugal vortex rotation creating an acoustic monopole. The surface-wave patch is a section of the sphere of radiation. The oppositely placed curved bodies of the sailfish and the flying fish act as concave acoustic mirrors about the monopole creating a reverberating bell-shaped cloak in between which vibrates the ear bones and bladders of the flying fish disorienting them. A cup of water firmly struck on a table induces a similar vibration of a purely radial mode. The sailfish circles around the school at a depth where the wind induced underwater toroidal motion in the vertical plane becomes negl...
Scientific Reports, 2022
Origin of scale coupling may be clarified by the understanding of multistability, or shifts betwe... more Origin of scale coupling may be clarified by the understanding of multistability, or shifts between stable points via unstable equilibrium points due to a stimulus. When placed on a glasstop hotplate, cobs of corn underwent multistable autonomous oscillation, with unsteady viscous lubrication below and transitional plumes above, where the buoyancy to inertia force ratio is close to ≥ 1.0. Subsequently, viscous wall-frictional multistability occurred in six more types of smooth fruit with nominal symmetry. Autonomous motion observed are: cobs roll, pitch and yaw; but green chillies, blueberries, tropical berries, red grapes, oblong grapes and grape tomatoes roll and yaw. The cross products of the orthogonal angular momentum produce the observed motion. The prevalence of roll and yaw motion are the most common. Lubricant film thickness h$$\propto$$ ∝ U/(TF), for cob mass F, tangential velocity U and temperature T. In heavier cobs, the film thins, breaking frequently, changing stabilit...
Proceedings of the 38th IEEE Conference on Decision and Control (Cat. No.99CH36304)
Recent developments in two approaches to hydrodynamic flow control are considered. One is concern... more Recent developments in two approaches to hydrodynamic flow control are considered. One is concerned with the closed-loop large-scale control of maneuvering of biologically-inspired small underwater vehicles in a disturbed littoral ocean environment. The other is the small-scale closed-and open-loop control of turbulence in a boundary layer developing on the outer surface of an ocean going vehicle. Theoretical and experimental progress made are described. The former type appears to be well amenable to closed-loop active control with the potential payoff of a high degree of precision in maneuvering. In the latter type, an active open-loop control appears to have the best potential for turbulence quieting and drag reduction. The paper is limited to exploratory work carried out by the author.
Journal of Fluids Engineering, 2018
The propulsors of organisms from paramecia to dolphins have ball-and-socket jointed bases that al... more The propulsors of organisms from paramecia to dolphins have ball-and-socket jointed bases that allow large-amplitude, low-friction swings. Their olivo-cerebellar control also remains unchanged. Yet, the propulsive surfaces of small animals vary widely from flagellar filaments (0 < Re < 5) to flapping fins (Re > 20) with an intermediate range of Reynolds number (5 < Re < 20) where both types are present in the same swimming animal. Analysis suggests that these unsteady surfaces are mechanical oscillators coupled to their nonlinear wakes. A low-friction-driven oscillator that can interact with the oscillators of models or live swimming and flying animals could help us understand the hydro-structural events prompting the evolution of such surfaces at specific Re values. A gearless underdamped (in air) hemispherical motor oscillator is described where energetic efficiency increases by a factor of eight as the forces drop by a factor of ten from 10 N. The electrical effici...
Public reporting for this collection of information is estimated to average 1 hour per response, ... more Public reporting for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports,
IEEE Journal of Oceanic Engineering, 2016
This paper has supplementary downloadable material available at explore.ieee.org, provided by the... more This paper has supplementary downloadable material available at explore.ieee.org, provided by the author. This includes seven multimedia WMV and MP4 format movie clips, which show the workings of the slosh-or-spin propulsor described in this paper. This video material is 31 MB in size. The supplementary material also contains a text file of figures in support of the claims in the paper. Digital Object Identifier 10.
Scientific reports, 2013
Functioning as sensors and propulsors, cilia are evolutionarily conserved organelles having a hig... more Functioning as sensors and propulsors, cilia are evolutionarily conserved organelles having a highly organized internal structure. How a paramecium's cilium produces off-propulsion-plane curvature during its return stroke for symmetry breaking and drag reduction is not known. We explain these cilium deformations by developing a torsional pendulum model of beat frequency dependence on viscosity and an olivo-cerebellar model of self-regulation of posture control. The phase dependence of cilia torsion is determined, and a bio-physical model of hardness control with predictive features is offered. Crossbridge links between the central microtubule pair harden the cilium during the power stroke; this stroke's end is a critical phase during which ATP molecules soften the crossbridge-microtubule attachment at the cilium inflection point where torsion is at its maximum. A precipitous reduction in hardness ensues, signaling the start of ATP hydrolysis that re-hardens the cilium. The c...
Modeling of flapping-fin propulsion with Stuart-Landau oscillator equation 1 AREN M. HELLUM 2 , P... more Modeling of flapping-fin propulsion with Stuart-Landau oscillator equation 1 AREN M. HELLUM 2 , PROMODE R. BANDYOPADHYAY, Naval Undersea Warfare Center, Newport, RI -Recently, the lowest order thrust measurements in an abstracted twisting and flapping fin have been modeled using a van der Pol-like oscillator (JFM 702,. A Stuart-Landau oscillator is used here as a higher order model of the interaction of the low aspect ratio flapping fin with its downstream thrust-producing reverse Karman vortex street. "Quasi-steady" equations for the forces produced on flapping fins or wings by the surrounding fluid assume that the lift and drag coefficients are based on 'a g (t)', a time-variable angle of attack based on the fin's instantaneous position and velocity. In this work, a wake-modified angle of attack 'a(t)' is used, such that 'a = a g + a w ' where 'a w (t)' is based on the circulation in the wake. This modification of the geometric angle of attack 'a g ' is justified generally by the conservation of circulation within the fin-wake system, and we argue that a Stuart-Landau oscillator represents a good approximation of the circulation within the wake. Results of this modeling are compared with experimental data taken on the abstracted penguin wing planform; a strong quantitative agreement exists between the experimental and modeled systems. We also model the effects of Reynolds number and the dependence of system oscillation lock-in on initial condition.
Low order oscillatory modeling of the inner layer of turbulent boundary layers 1 PROMODE R. BANDY... 
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Papers by Promode R Bandyopadhyay