Numerical Investigation of Flow over Orthoconic Structure

Orthoconic cephalopods were classic fossil nautiloids of underwater communities whose locomotion in swimming and special annulations around the shell are understudied. We intend to investigate the marine ecology and hydrodynamic characteristics of straight orthoconic shells in a moving fluid, which can shed light on potential applications in morphologic design for underwater vehicles. The geometry of the orthoconic shell model is determined based on measurements of the sculpture and size from fossil specimens. Direct numerical simulations of incompressible flow over the orthoconic shell are performed using two different angles of attack (AoA): 0° and 180°, to mimic different swimming directions of orthoconic cephalopods. The Reynolds number considered in the present work ranges in the order from O(10) to O(1000). Flow features and hydrodynamic forces around the orthoconic shell and in the wake are characterized. From the preliminary results, critical transition from steady to unsteady flow falls between Re=500 and 1000 for the AoA 0° case. In the future, analysis of an annulated orthoconic shell model will be investigated, which could provide insights into the control of the canonical flow over a canonical cone structure in engineering applications.