Morphologic Optimal Design of Bionic Undulating Fin Based on Computational Fluid Dynamics

Biomimetic design takes principles from nature to employ in engineering problems. Such designs are hoped to be quiet, efficient, robust, and versatile, having taken advantage of optimization via natural selection. In our initial work, an undulating robotic fin actuated by shape memory alloy (SMA) is developed, the design of which is inspired by the pectoral fin of stingray. The robotic fin has nine individually actuated SMA fin rays which are linked by a thin latex sheet. This remarkable robotic fin moves by oscillating its SMA actuators out of phase and thereby passing a travelling, propulsive wave along the fins length from anterior to posterior part. A computational fluid dynamics (CFD) based comparison of optimal thrust and efficiency generation among four typical fin undulating swimming models with different amplitude envelopes have been discussed in detail. Here, we seek to complement those studies by considering the influence of fin morphologic. We first review the biological background of ray-like swimming of Batoid fishes. Then give a brief introduction on initial related work including: design of our mechanical fin and CFD work. Subsequently, we focus on morphologic optimal design of our developed bionic undulating fin by taking the advantages of three-dimensional CFD method. This robotic fin has potential application as a propulsor for future underwater vehicles, in addition to being a valuable scientific instrument in understanding the swimming mechanics of the stingray and similar fish.