Self-propulsion of fishes-like undulating hydrofoil: A unified kinematics based unsteady hydrodynamics study

Thekkethil, Namshad; Sharma, Atul; Agrawal, Amit

doi:10.1016/j.jfluidstructs.2020.102875

Cited by 34 publications

(6 citation statements)

References 43 publications

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“…2018; Ryu et al. 2019; Thekkethil, Sharma & Agrawal 2020 a ). This definition is more suitable for isolated propulsors, such as oscillating foils and plates.…”

Section: Effects Of Chordwise Deformationmentioning

confidence: 99%

Vortex dynamics and hydrodynamic performance enhancement mechanism in batoid fish oscillatory swimming

et al. 2021

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The effects of chordwise deformation and the half-amplitude asymmetry on the hydrodynamic performance and vortex dynamics of batoid fish have been numerically investigated, in which the two parameters were represented by the wavenumber ( $W$ ) and the ratio of the half-amplitude above the longitudinal axis to that below ( $HAR$ ). Fin kinematics were prescribed based on biological data. Simulations were conducted using the immersed boundary method. It was found that moderate chordwise deformation enhances the thrust, saves the power and increases the efficiency. A large $HAR$ can also increase thrust performance. By using the derivative-moment transformation theory at several subdomains to capture the local vortical structures and a force decomposition, it was shown that, at high Strouhal numbers ( $St$ ), the tip vortex is the main source of thrust, whereas the leading-edge vortex (LEV) and trailing-edge vortex weaken the thrust generation. However, at lower $St$ , the LEV would enhance the thrust. The least deformation ( $W=0$ ) leads to the largest effective angle of attack, and thus the strongest vortices. However, moderate deformation ( $W=0.4$ ) has an optimal balance between the performance enhancement and the opposite effect of different local structures. The performance enhancement of $HAR$ was also due to the increase of the vortical contributions. This work provides a new insight into the role of vortices and the force enhancement mechanism in aquatic swimming.

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“…2018; Ryu et al. 2019; Thekkethil, Sharma & Agrawal 2020 a ). This definition is more suitable for isolated propulsors, such as oscillating foils and plates.…”

Section: Effects Of Chordwise Deformationmentioning

confidence: 99%

Vortex dynamics and hydrodynamic performance enhancement mechanism in batoid fish oscillatory swimming

et al. 2021

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“…Those three forces are time-varying parameters. It will be effective to enlarge F x to realize high propulsive efficiency [31] and to narrow F y to realize good stability [32].…”

Section: Resultsmentioning

confidence: 99%

Experiment for Effect of Attack Angle and Environmental Condition on Hydrodynamics of Near-Surface Swimming Fish-Like Robot

Xue

Bai

et al. 2023

Applied Bionics and Biomechanics

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Fish-like robot is a special autonomous underwater vehicle with broad application prospects. Some previous studies concentrated on the hydrodynamics of free-swimming fish-like robots. But the hydrodynamic performance of fish-like robot swimming with a tilt angle in constrained space has not been well studied, and the influence of environmental wave and current on its is also still unclear. In this paper, the experiment devices, including a physical fish-like robot, a hydrodynamics measurement platform, and a six-axis force sensor, are used to study the effect of attack angle and environmental condition on the hydrodynamics of near-surface swimming fish-like robot. Nine attack angles, five oscillating amplitudes, and three environmental conditions are analyzed in the experiments. It shows that thrust force decreases when caudal fin passes above water surface, but the increased difference between gravity force and buoyancy force will compensate the decreased force generated by caudal fin when fish-like robot swims with certain dive angle. The extra reaction force generated by solid bottom boundary will promote the thrust force and vertical force. The surface water wave condition or surface water current condition also has obvious effects on hydrodynamic performance. This paper provides a new perspective to the research on the hydrodynamic performance of fish-like robot and will do favor in the development of fish-like robot.

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“…7. The literature around numerical experiments of Anguilliform swimmers shows that a reasonable approximation for modeling Anguilliform swimming is to set A to 0.1 and α to 1 [14,15,17,47,48]. While only [15,17] used the data from Tytell directly for their simulations, the others performed a least squares fit on the envelope and adapted it to the polynomial envelope proposed by Videler and Nolet [44].…”

Section: Mathematical Description Of Fish Motionmentioning

confidence: 99%

IKA-FLOW : A Flexible Body Overset Mesh Implementation for Fish Swimming

Coe

Gutschmidt

2023

OpenFOAM J

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Simulation of inertial aquatic swimmers requires fluid structure interactions with temporal body geometry deformation. In practice, his results in a change of the computational domain boundaries that represent the ”swimmer.” These simulations are traditionally done sing body-fitted mesh and mesh morphing methods, but have drawbacks of negative cell volumes and small time-steps to account for the complex swimming motion. In contrast, the overset mesh method, also provided by OpenFOAM®, overcomes most of the drawbacks of the mesh morphing method at the expense of interpolation error. The current OpenFOAM® overset motion library only supports rigid body motion and cannot be used to resolve a body undergoing undulation. A modified motion solver is presented that allows for the complex mesh motion of an overset mesh for four body-caudal fin (BCF) virtual swimmers. The results of this solver are compared with published data of body-fitted meshes. The effect of different simulation parameters (including number of solving iterations, time delay, and temporal resolution) is investigated. Additionally, a novel simulation and comparison of the Ostraciiform locomotion mode with Anguilliform, Carangiform, and Thunniform modes are made investigating the wake, drag and lift. It is concluded that fish undulation has a marked effect on reducing lift generation. Lastly, a comparison of turbulence models (Spalart-Allmaras, k − ω SST, and k − kL − ω) at multiple Reynolds numbers shows that all three models have similar performance at lower Reynolds numbers but diverge at higher numbers.

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Self-propulsion of fishes-like undulating hydrofoil: A unified kinematics based unsteady hydrodynamics study

Cited by 34 publications

References 43 publications

Vortex dynamics and hydrodynamic performance enhancement mechanism in batoid fish oscillatory swimming

Vortex dynamics and hydrodynamic performance enhancement mechanism in batoid fish oscillatory swimming

Experiment for Effect of Attack Angle and Environmental Condition on Hydrodynamics of Near-Surface Swimming Fish-Like Robot

IKA-FLOW : A Flexible Body Overset Mesh Implementation for Fish Swimming

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