We present experimental force and power measurements demonstrating that the required to propel an actively swimming, streamlined, fish-like body is significantly smaller than needed tow straight rigid at same speed U . The data have been obtained through accurate motion on a laboratory robotic mechanism, 1.2 m long, covered with flexible skin equipped tail fin, Reynolds numbers up 10 6 , turbulence stimulation. lateral of in form travelling wave wavelength λ varying amplitude along length,...

Significant progress has been made in understanding some of the basic mechanisms force production and flow manipulation oscillating foils for underwater use. Biomimetic observations, however, show that there is a lot more to be learned, since many functions details fish fins remain unexplored. This review focuses primarily on experimental studies the, at least partially understood, mechanisms, which include 1) formation streets vortices around behind two- three-dimensional propulsive foils;...

ABSTRACT We consider the motions and associated flow patterns of a swimming giant danio (Danio malabaricus). Experimental flow-visualization techniques have been employed to obtain unsteady two-dimensional velocity fields around straight-line 60 ° turn fish in centerline plane depth. A three-dimensional numerical method is also predict total field through simulation. Comparison experimental vorticity shows good agreement. The morphology, with its narrow peduncle region, allows for smooth...

It is shown experimentally that free shear flows can be substantially altered through direct control of the large coherent vortices present in flow. First, flow-visualization experiments are conducted Kalliroscope fluid at Reynolds number 550. A foil placed wake a D-section cylinder, sufficiently far behind cylinder so it does not interfere with vortex formation process. The performs heaving and pitching oscillation frequency close to Strouhal while also move forward constant speed. By...

We employ a three-dimensional, nonlinear inviscid numerical method, in conjunction with experimental data from live fish and fish-like robotic mechanism, to establish the three-dimensional features of flow around body swimming straight line, identify principal mechanisms vorticity control employed swimming. The computations contain no structural model for hence recoil correction. First, we show near-body structure produced by travelling-wave undulations bodies tuna giant danio. As revealed...

In order to perform underwater surveillance, autonomous vehicles (AUVs) require flexible, light-weight, reliable and robust sensing systems that are capable of flow detecting objects. Underwater animals like fish a similar task using an efficient ubiquitous sensory system called lateral-line constituting array pressure-gradient sensors. We demonstrate here the development arrays polymer microelectromechanical (MEMS) pressure sensors which flexible can be readily mounted on curved surfaces...

We report the development of a new class miniature all-polymer flow sensors that closely mimic intricate morphology mechanosensory ciliary bundles in biological hair cells. An artificial bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The nature single link confirmed X-ray diffraction (XRD) Fourier transform infrared spectroscopy (FTIR). Rheology...

In an effort to improve the situational awareness and obstacle avoidance of marine vehicles, we fabricate, package characterize Pb (Zr0.52Ti0.48)O3 thin-film piezoelectric pressure sensor arrays for passive fish-like underwater sensing. We use floating bottom electrode in designing which made able detect very low frequency range (down 0.1 Hz) water. The proposed array sensors is capable locating objects by transducing variations generated stimulus. are packaged into 2 × 5 on a flexible...

Evolution bestowed the blind cavefish with a resourcefully designed lateral-line of sensors that play an essential role in many important tasks including object detection and avoidance, energy-efficient maneuvering, rheotaxis etc. Biologists identified two types vital on fish bodies called superficial neuromasts canal are responsible for flow sensing pressure-gradient sensing, respectively. In this work, we present design, fabrication experimental characterization biomimetic polymer...

We present the development and testing of superficial neuromast-inspired flow sensors that also attain high sensitivity resolution through a biomimetic hyaulronic acid-based hydrogel cupula dressing. The inspiration comes from spatially distributed neuromasts blind cavefish live in completely dark undersea caves; enable fish to form three-dimensional object maps, enabling them maneuver efficiently cluttered environments. A canopy shaped electrospun nanofibril scaffold, inspired by cupular...

Predicting motions of vessels in extreme sea states represents one the most challenging problems naval hydrodynamics. It involves computing complex nonlinear wave-body interactions, hence taxing heavily computational resources. Here, we put forward a new simulation paradigm by training recurrent type neural networks (RNNs) that take as input stochastic wave elevation at certain state and output main vessel motions, e.g. pitch, heave roll. We first compare performance standard RNNs versus GRU...

In this paper, we conducted a selective review on the recent progress in physics insight and modeling of flexible cylinder flow-induced vibrations (FIVs). FIVs circular cylinders include vortex-induced (VIVs) wake-induced (WIVs), they have been center fluid-structure interaction (FSI) research past several decades due to rich engineering significance. First, summarized new understanding structural response, hydrodynamics, impact key properties for both isolated multiple cylinders. The...

The use of Polyvinylidene Fluoride (PVDF) based piezoelectric nanofibers for sensing and actuation has been reported widely in the past. However, most cases, PVDF nanofiber mats have used applications. This work fundamentally characterizes a single electrospun demonstrates its application as element nanoelectromechanical sensors (NEMS). were spun by far field electrospinning (FFES) process complete material characterization was conducted means scanning electron microscope (SEM) imaging,...

The paper reports the design, fabrication and experimental results of a liquid crystal polymer (LCP) membrane-based pressure sensor for flow rate direction sensing applications. Elaborate testing demonstrating sensors' performance as an airflow have been illustrated validated with theory. MEMS sensors using LCP membrane structural material show higher sensitivity reliability over silicon counterparts. developed device is highly robust harsh environment applications such atmospheric wind...

Abstract In this work a cephalopod-like deformable body that fills an internal cavity with fluid and expels it to propel escape manoeuvre, while undergoing drastic external shape change through shrinking, is shown employ viscous as well mainly inviscid hydrodynamic mechanisms power impressively fast start. First, we show recovery of added-mass energy enables shrinking rocket in dense flow achieve greater speed than identical vacuum. Next, extend the results Weymouth & Triantafyllou ( J....

A flow sensor inspired by the harbor seal's whiskers has been calibrated in a towing tank and tested at sea. The whiskers' undulatory, asymmetric geometry causes wide range of self-excited vibrational responses. These vibrations are measured mechanically used to determine oncoming direction velocity. Calibration runs show vibration amplitude cross-flow from ≈0.1 0.6 times whisker diameter, depending on direction. Deflection inline-flow ranges ≈0 0.08 Field tests confirm ability be...

A major difference between manmade underwater robotic vehicles (URVs) and undersea animals is the dense arrays of sensors on body latter which enable them to execute extreme control their limbs demonstrate super-maneuverability. There a high demand for miniaturized, low-powered, lightweight robust that can perform sensing URVs improve maneuverability. In this paper, we present design, fabrication experimental testing two types microelectromechanical systems (MEMS) benefit situational...

Emissions from a dry bulk vessel operating on biofuel blend were measured. Although marginal differences observed in CO 2 emissions combustion compared to conventional marine fuels, life cycle can be reduced by up 40%.

In this study, we present a method to construct meter-scale deformable structures for underwater robotic applications by discretely assembling mechanical metamaterials. We address the challenge of scaling up nature-like while remaining structurally efficient combining rigid and compliant facets form custom unit cells that assemble into lattices. The generate controlled local anisotropies architect global deformation structure. resulting flexibility allows better unsteady flow control enables...

We introduce DeepVIVONet, a new framework for optimal dynamic reconstruction and forecasting of the vortex-induced vibrations (VIV) marine riser, using field data. demonstrate effectiveness DeepVIVONet in accurately reconstructing motion an off--shore riser by sparse spatio-temporal measurements. also show generalization our model extrapolating to other flow conditions via transfer learning, underscoring its potential streamline operational efficiency enhance predictive accuracy. The trained...