We calculate optimal driving motions for a fin ray in a two-dimensional inviscid fluid, which is a model for caudal fin locomotion. The driving is sinusoidal in time, and consists of heaving, pitching and a less-studied motion called ‘shifting’. The optimal phases of shifting relative to heaving and pitching for maximum thrust power and efficiency are calculated. The optimal phases undergo jump...

Bionic underwater robot is a new-type underwater robot which propelled and controlled by several bionic fins. Heaving motion is an indispensably function for most bionic underwater robots. Bionic bladder system is an apparatus which can realize both heaving and pitching control. It was inspired by biologic fish’s bladder. It was composed of a cylinder, a piston, a pipe, a rolling guide, two bal...

A design study has been made of a wave energy converter in the form of a heaving buoy reacting against an internal moving mass. Phase control has been obtained by modulating the stiffness of the spring governing the moving mass. Promising results, agreeing closely with linear theory, have been obtained with two shapes of buoy. Mean annual captures of the order of 2OOW/tonne in a typical South U...

Oscillating type devices constitute a major class of offshore wave energy converters. In view of the characteristic of the wave energy in China that is low in energy density, a new heaving buoy wave energy device is designed. The paper introduces the basic components of the device, including buoys, support platform, submerged platform, anchor system and hydraulic power take-off, addresses the s...

The mechanism of pipe–soil interaction under frost heaving is complicated due to many factors affecting the system. In order analyze sensitivity various influencing and highlight relationship between pipe’s mechanical characteristics during heaving, a model based on semi-infinite elastic frozen soil foundation developed. Besides, indices characterizing influence their change law are emphaticall...

Flapping-wing kinematics for insect flight has been studied for decades, especially since engineers became interested in flapping-wing micro air vehicles (FWMAVs). Previous work mainly focused on understanding kinematic patterns employed by different insects from the perspective of their trajectories and aerodynamics, and on optimization of kinematic parameters to enhance the understanding. How...

The hydrodynamics and energetics of bioinspired oscillating mechanisms have received significant attentions by engineers and biologists to develop the underwater and air vehicles. Undulating and pure heaving (or plunging) motions are two significant mechanisms which are utilized in nature to provide propulsive, maneuvering, and stabilization forces. This study aims to elucidate and compare the ...

A pressure based implicit procedure to solve the Euler and Navier-Stokes equation is developed to predict transonic viscous and inviscid flows around the pitching and heaving airfoils with a high reslution scheme. In this process, nonorthogonal and non moving mesh with collocated finite volume formulation are used. In order to simulate pitching or heaving airfoil, oscillation of flow boundary c...

Absorption of wave energy may be considered as a phenomenon of interference between incident and radiated waves generated by an oscillating object; a wave-energy converter (WEC) that displaces water. If a WEC is very small in comparison with one wavelength, it is classified as a point absorber (PA); otherwise, as a 'quasi-point absorber'. The latter may be a dipole-mode radiator, for instance a...