Case study - Morphology of a Shark Nose
The gross morphology of the nasal region of a fish determines how flow behaves in this region, and therefore has an important influence on the fish's olfactory abilities (sense of smell). Life-sized rapid prototype models were generated from a 200 µm resolution CT scan which enabled the functional morphology to be investigated within a flow tank. This allowed researchers to explore how the different channels and grooves effect the water circulation within the nasal cavities.
►Read more on University of Bath website
Characteristics:
- Using CT to accurately build physical models featuring internal features
- Creation of highly accurate STL files representing the shark head and nasal cavities
- Rapid prototyping was used to create plastic models which could be used with in a flow tank
Thanks to
Natural History Museum, London: R. Abel, J. Maclaine • University of Cambridge: T. Nickels, T. Clark • University of Bath: Z. Wang, J. Cox
I Image Acquisition
After removal of the specimen from the preservative it was mounted for CT scanning. Scanning was performed using an HMXST 225 CT system (Metris X-Tek, Tring, UK). The X-rays were generated from a tungsten target using a voltage and current of 180 kV and 105 µA, respectively. The radial projections were reconstructed into a three-dimensional matrix of 1897×1830×630 (L×W×H) 124.5 µm cubic voxels.
II STL Generation
The DICOM images were imported into ScanIP. The Floodfill segmentation tool was used to fill unwanted internal cavities whilst preserving the nasal cavity. Some features in the olfactory chamber were manually refined using the Paint tool. To generate the STL file, volume and topology preserving smoothing was utilised to smooth the segmentation without losing the small features of the lamellae.
III Simulation
The resulting plastic models created from the STL files were then placed in a water flow tank. Varying water flow rates were used to investigate how the features of the sharks head affected the direction of the water flow into the nasal cavities. A dye was used to help visualise the flow. It was found that the exterior channels and grooves directed water into the nasal cavity which then circulates before exiting from a different opening. ►Videos
Model Tree to view/hide the layers of the model.
Water Flow Tank Video 1
The transparent plastic RP models created from the ScanIP STL files were used in a flow tank to observe how water flows in and around the nasal region of the hammerhead shark. This video shows the full nasal region with the dye highlighting how the outer channels the oncoming water in to the nasal region.
Water Flow Tank Video 2
The transparent plastic RP models created from the ScanIP STL files were used in a flow tank to observe how water flows in and around the nasal region of the hammerhead shark. This video shows how the water is directed in to the entrance of the nasal region.
Water Flow Tank Video 3
The transparent plastic RP models created from the ScanIP STL files were used in a flow tank to observe how water flows in and around the nasal region of the hammerhead shark. This video shows how the water circulates at the end of the nasal region so that it can then exit the shark.
