title: Theoretical and computational fluid dynamics of an attached remora (Echeneis naucrates).
abstract: Remora fishes have a unique dorsal suction pad that allows them to form robust, reliable, and reversible attachment to a wide variety of host organisms and marine vessels. Although investigations of the suction pad have been performed, the primary force that remoras must resist, namely fluid drag, has received little attention. This work provides a theoretical estimate of the drag experienced by an attached remora using computational fluid dynamics informed by geometry obtained from micro-computed tomography. Here, simulated flows are compared to measured flow fields of a euthanized specimen in a flow tank. Additionally, the influence of the host's boundary layer is investigated, and scaling relationships between remora features are inferred from the digitized geometry. The results suggest the drag on an attached remora is similar to that of a streamlined body, and is minimally influenced by the host's viscous boundary layer. Consequently, this evidence does not support the hypothesis that remoras discriminate between attachment locations based on hydrodynamic considerations. Comparison of the simulated drag with experimental friction tests show that even at elevated swimming speeds it is unlikely that remoras are dislodged by drag alone, and furthermore that larger remoras may be more difficult to dislodge than smaller remoras indicating that they become more suited to attachment as they mature.
authors.affiliation: Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA. Electronic address: michael.beckert@gatech.edu.
authors.forename: Michael
authors.initials: M
authors.lastname: Beckert
authors.affiliation: Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA.
authors.forename: Brooke E
authors.initials: BE
authors.lastname: Flammang
authors.affiliation: Department of Mechanical Engineering, Grove City College, Grove City, PA 16127, USA; Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Anderson
authors.affiliation: Advanced Concepts Laboratory, Georgia Tech Research Institute, Atlanta, GA 30332, USA.
authors.forename: Jason H
authors.initials: JH
authors.lastname: Nadler
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005399:Fishes / Q000502:physiology*; D057446:Hydrodynamics; D008954:Models, Biological; D014741:Video Recording
keywords: Attachment; Boundary layer; Drag; Hitchhiking; Suction pad