A Lagrangian Analysis of Vortex Formation in the Wake behind a Transversely Oscillating Cylinder
- 12 Downloads
A vortex pair + single vortex (P+S) wake behind a transversely oscillating cylinder is investigated from the Lagrangian point of view. The Lagrangian coherent structures (LCSs) of the flow are computed to analyze formation of vortices in the wake. An asymmetric vortex street is obtained by using a dynamic mesh method. The corresponding vorticity field is found to agree well with real experiments. The LCSs are approximated by ridges of the finite-time Lyapunov exponents computed from transient velocity fields. The formation process is investigated using the vorticity field and the LCSs. It is found that details of the wake pattern are sensitive to initial oscillation conditions, and that the cylinder motion causes an early roll-up of boundary layers to form new vortex structures in the wake. Lagrangian description of the flow with the help of the LCSs provides further details about formation of vortices in the cylinder flow and helps to get a new insight into the flow structure in the wake region.
Keywordsvortex street Lagrangian coherent structure vorticity
Unable to display preview. Download preview PDF.
- 19.Samelson, R.M. and Wiggins, S., Lagrangian Transport in Geophysical Jets and Waves: The Dynamical Systems Approach, Interdiscip. Appl. Math., vol. 31, New York: Springer, 2006.Google Scholar
- 28.Budyansky, M.V., Goryachev, V.A., Kaplunenko, D.D., Lobanov, V.B., Prants, S.V., Sergeev, A. F., Shlyk, N. V., and Uleysky, M.Yu., Role of Mesoscale Eddies in Transport of Fukushima-Derived Cesium Isotopes in the Ocean, Deep Sea Res. Part 1 Oceanogr. Res. Pap., 2015, vol. 96, pp. 15–27.CrossRefGoogle Scholar
- 29.Prants, S.V., Ponomarev, V. I., Budyansky, M.V., Uleysky, M.Yu., and Fayman, P.A., Lagrangian Analysis of Mixing and Transport of Water Masses in the Marine Bays, Izv. Atmos. Ocean. Phys., 2013, vol. 49, no. 1, pp. 82–96; see also: Izv. Akad. Nauk SSSR. Fiz. Atmos. Okeana, 2013, vol. 49, no. 1, pp. 91–106.CrossRefGoogle Scholar