Statistical hydrodynamics modeling of two-dimensional undulating fins for robotic fish

Undulation fishes, whose propulsion is mainly achieved by undulating ribbon fins, are good at maneuvering or stabilizing at low speeds. This paper suggests and proposes a two-dimensional approximate computational model before presenting an initial analysis on undulation propulsion scheme. It is believed that this mode has a better potential for exploitation in artificial underwater systems. Hydrodynamics of two-dimensional undulating fins under a series of kinematical parameter sets is explored via numerical simulation. The periodicity of undulation forces and moments is herein studied. The effects of wavelength, undulation frequency, and undulation amplitude are investigated. Furthermore, a dimensionless two-parameter model for undulation surge force is established with a given wavelength (for example, a single wavelength or dual wavelength). The work in this paper is able to provide studies on bionic undulation mode. It has also formed a meaningful basis for three-dimensional hydrodynamics and corresponding control methods in bionic undulation robots.