The use of computational fluid dynamics in reconstructing the hydrodynamic properties of graptolites

Abstract

Graptolites are some of the most commonly preserved Silurian planktonic organisms. The interpretation of graptolite functional morphology is rendered problematic by their lack of close modern analogues or homologues. Physical modelling of graptolites has explained some aspects of their hydrodynamic behaviour, such as their orientation relative to currents and their rate of response to new directions of water flow. However, this technique is slow and laborious and the accuracy of the physical models limits the level of detail that can usefully be studied. Computational fluid dynamics (CDF) are routinely used in engineering applications in order to overcome these limitations. CFD models of graptolites have been generated and the results tested against the known outcomes of physical models. Three-dimensional virtual models of graptolites, generated to true scale, are exposed to computed fluid flow from a variety of orientations. Cross-checks with physical modelling show that these iterative computational solutions produce verifiable results. Virtual graptolites can be modified at will and exposed to a range of current velocities. Results suggest that major improvements in our understanding of graptolite functional morphology will result from further use of this novel technique.