AUV shapes - Combining the Practical and Hydrodynamic Considerations

This paper reports on recent computational fluid dynamics (CFD) work, revisiting the concept of the tear drop shaped laminar flow hull and compares it with practical drag data, both laminar body and torpedo shape, that has been accumulated over the years. A short vehicle of length /diameter ratio 3 to 4 can be a more practical proposition with little if any increase in drag coefficient (Cd). The laminar flow body, an idea largely discarded in the 1990s due to practical build difficulties and shortfall in expected performance, may still have a lower Cd if care is taken with the placement of external ancillaries.