# Applied and Computational Mathematics Seminar

## Seminar Details

- Speaker:
- Cathal Cummins
- Affiliation:
- Heriot-Watt University/Maxwell Institute
- Title:
- A separated vortex ring underlies the flight of the Jinny Joe
- Time:
- 1PM Monday, 30 September 2019
- Location:
- SCN 1.25, O'Brien Centre for Science (North)

Large (macro) bodies, such as whales and bumblebees, move about using thin membranes (fins and wings etc.). Very small (micro) bodies, such as spermatozoa, use slender filaments for movement. At the macroscale, locomotion is achieved by imparting momentum to the surrounding fluid. At the microscale, such a strategy would be foiled by large viscous drag forces; hence, locomotion is achieved by exploiting drag forces. At some lengthscale, there is a shift from using thin membranes to using hairs to move. In this talk, we will explore the hydrodynamic basis of locomotion in this "mesoscale" realm, with the common dandelion fruit (Jinny Joe) as our tour guide.

### References

Cummins, C., Seale, M., Macente, A., Certini, D., Mastropaolo, E., Viola, I. M., & Nakayama, N. (2018). A separated vortex ring underlies the flight of the dandelion. Nature, 562(7727), 414–418. https://doi.org/10.1038/s41586-018-0604-2
Seale, M., Cummins, C., Viola, I. M., Mastropaolo, E., & Nakayama, N. (2018). Design principles of hair-like structures as biological machines. Journal of the Royal Society Interface, 15(142). https://doi.org/10.1098/rsif.2018.0206
Cummins, C., Viola, I. M., Mastropaolo, E., & Nakayama, N. (2017). The effect of permeability on the flow past permeable disks at low Reynolds numbers. Physics of Fluids, 29(9). https://doi.org/10.1063/1.5001342
### Biography

Cathal is an interdisciplinary applied mathematician, and holds the position of Assistant Professor at the School of Mathematical and Computer Sciences of Heriot-Watt University. He obtained his BSc in Mathematical Physics from University College Dublin in 2009. He was awarded an MSc in Mathematical Modelling in 2011 and a PhD in Applied Mathematics in 2015. His previous academic appointments were as a postdoctoral fellow at University College Dublin (2015) and University of Edinburgh (2016-2019).

His research has won international prizes in physics and in applied mathematics and he shares his passion for mathematics as an award-winning scientific speaker. To date, Cathal has published papers on the mathematics of Guinness, interfacial flows, wave energy converters, and the aerodynamics of nature's tiniest fliers.

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