The complexity in structure and locomotion of cephalopods, such as the octopus, poses difficulties in modeling and simulation. Their slender arms, being highly agile and dexterous, often involve intense deformations, which are hard to simulate accurately, while simultaneously ensuring numerical stability and low diffusion of the transient motion results. Within the immersed-boundary framework, this paper focuses on an arm geometry performing prescribed motions that reflect octopus locomotion. The method is compared with a finite-volume numerical approach to determine the mesh requirements that must be employed for sufficiently capturing, not only the near wall viscous flow, but also the off-body vortical flow field in intense forced motions. The objective is to demonstrate and exploit the generality of the immersed boundary approach to complex numerical simulations of deforming geometries. Incorporation of arm deformation was found to increase the output thrust of a single-arm system. It was further found that sculling motion combined with arm undulations provides an effective propulsive scheme for an octopus-like arm.
Bibliographical noteFunding Information:
This work was supported in part by the European Commission (EC) and the General Secretariat for Research and Technology (GSRT) of the Hellenic Ministry of Education via the ESF-GSRT HYDRO-ROB Project [ PE7(281) ] and the EC-ERDF BIOSYS-KRIPIS Project [ MIS-448301 (2013SE01380036) ]. Parts of these simulations were carried out on the CaSToRC High-Performance Computing (HPC) system of the LINKSCEEM/Cy-Tera resources (Project pro14a108) and the PRACE Tier-1 HPC system (Project CepFlow, 12DECI0048). The authors would like to thank B. Hochner, T. Flash, M. Sfakiotakis, X. Zabulis, M. Kuba, J. Oikonomidis, A. Chatzidaki, Th. Evdaimon, and S. Stefanou, for their assistance with these studies.
© 2015 Elsevier Ltd.
- Aquatic locomotion
- Biological propulsion
- Computational fluid dynamics (CFD)
- Immersed boundary method
- Large deformations