For a wide variety of scientific and commercial reasons, various animals have been equipped with satellite-based tracking transmitters for several years. This also applies to seals. With precise, time-stamped tracking, the seals’ breeding and foraging behavior can be studied in greater detail. The greatest advantage of satellite-based tracking is that the precise position of the animals can be received directly at the workplace. Otherwise, such tracking is only possible, if at all, in limited areas with the aid of aerial reconnaissance.
For satellite-based tracking, animals must be fitted with transmitters. These transmitters are attached to the animals’ hindquarters or backs using epoxy resin. In the scientific world, there is extremely controversial debate regarding the extent to which the transmitter influences the animals’ natural behavior. Some time ago, seals were found with transmitters that were severely emaciated. To investigate whether a change in water flow caused by the transmitter was the reason for the weight loss, FlowMotion was commissioned to simulate the flow around a seal with and without a transmitter. For this purpose, a 3D model of a grey seal’s shape was created on a computer using photographs. When meshing the computational grid, care was taken to ensure the highest possible level of calculation accuracy.
The simulations showed that the flow resistance, which primarily influences the animal’s maximum speed and energy consumption, is increased by approximately 12% due to the transmitter. However, the torque around the horizontal axis also changes by approximately 35%. Furthermore, it was shown that regions of low wall shear stress form on the seal’s back in the wake of the transmitter. Adhesions were found in these areas on the emaciated seals that were discovered.
The relationship between the simulation results and the possible resulting changes in behavior was examined in greater detail during the subsequent course of the project.
