Measurement of drag coefficients of 3D printed inflated ammonite shells

Activity: Talk or presentationOral presentation


Ammonite shells have been used over the last ten years as models to test research questions related to a theory on the evolutionary trade-offs proposed by Shoval et al. [1,2]. Ammonoids evolved over geological timescales and survived several mass extinction events. Raup parameterised their external geometry using only 3 parameters labelled W, D and S. These parameters describe the growth of the radius with each whorl, the constant ratio between the inner and outer shell radii, and the shell cross section, respectively [3]. The seminal work on measurement of drag coefficients of different ammonite shells carried out by Chamberlain included mainly measurements on shells with circular aperture (S=1) [4]. The original dataset gave thus little insight on the hydrodynamic efficiency and manoeuvrability of depressed (S<1) and inflated (S>1) shells, thereby limiting the understanding of theory of evolution and trade-off to explain constraints and objective functions in the W-D-S morpho-space occupied by the ammonite shells.
Chamberlain’s datasheet needs to be populated further with data of depressed and inflated shells. As ammonites are now extinct, experimental measurements of drag coefficient were performed on 64 different 3D printed ammonite shells (36-00orientation, 28-300 orientation). The 3D printed shells are 60 mm in diameter, and the shape of the shells vary based on the 3 Raup’s geometrical parameter. Thus, the existing dataset can be populated with additional information of hydrodynamic efficiency of inflated shells. Further, the study of the drag coefficient study at 0-degree orientation has also been performed.
Period13 Sept 202315 Sept 2023
Event titleInternational Symposium on Palaeo-bioinspiration
Event typeConference
LocationParis, FranceShow on map
Degree of RecognitionInternational