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A Morphospace Evaluation of the Hydrodynamics of Ammonite Conch Structures

Semester: Summer 2023

Presentation description

Ammonite seashell morphology likely affected how these squid-like animals swam and interacted with the world around them. Still, we have few direct restrictions about the relative risks and opportunities presented by different aspects of each conch shape. We advance this study by generating hypothetical three-dimensional models of ammonoid conchs in the open-source software Blender. Then we use computational fluid dynamics to simulate water flow around the shells across a practical range of velocities. Trajectory analyses of the simulated drag measurements allow us to speculate on the scope of swimming velocities, jet propulsion strategies, and coasting patterns that would have best used these conch morphologies. Here, we specifically examine the gradient of conch morphology focused between umbilical exposure and whorl expansion, and the gradient between thickness and whorl expansion. We generate 9 conch models; simulate water flow at 11 velocities (1-50 cm/s); and record simulated drag forces (pressure and viscous). Our results add nuance to a long-held assumption that a highly streamlined oxyconic shape is the ideal shell with the lowest drag coefficient overall. Instead, we find a limited suite of behavioral advantages that employ an oxyconic shell: intense streamlining imparts reduced drag only once a sufficient size and velocity is reached. Purely serpenticonic forms, in contrast, produce middling drag in these low-speed simulations and suggest middling escape and coasting ability across a wide range of sizes and target velocities. We present results in the Westermann Morphospace to examine the first-order hydrodynamic risks and opportunities across the serpentine-to-oxycone and the spherocone-to-oxycone gradients of conch shapes. This data will further expand previously published experimental and simulation data and clarify the following directions for biomechanical investigation.|

Presenter Name: Brittney Hoskins
Presentation Type: Poster
Presentation Format: In Person
Presentation #34
College: Mines & Earth Sciences
School / Department: Geology and Geophysics
Research Mentor: Kathleen Ritterbush
Date | Time: Thursday, Aug 3rd | 9:00 AM