Multimedia

For the APS gallery of fluid motion, we prepared this video:

This video shows a volume rendering of a the vorticity magnitude generated by a bumblebee. The model bumblebee (see Publications for details, the results are published in PRL) in flying forward at 2.5 m/s and its Reynolds number is 2042. We used this simulation to get an idea what turbulence the bumblebee itself generates. With this knowledge, we designed a turbulent inlet to study the same model in turbulence.


The next video shows the same model insect, but in a turbulent inflow. The relative turbulence intensity, which is the RMS value of the velocity fluctuations normalized by the mean forward flight velocity, is 100%. Thus, the environment is highly turbulent. However, the model still generates the same lift and thrust as in the laminar case, if statistically averaged. Of course, fluctuations occur, thus the turbulence causes vibrations. On the other hand, these perturbations do not destroy the vortex system, most prominently the leading edge vortex.