Fast-response underwater TSP investigation of subcritical instabilities of a cylinder in crossflow

Publikations-Art

Arbeitspapier/Diskussionspapier

Autoren

Capone, A.; Klein, C.; Di Felice, F.; Beifuss, U.; Miozzi M.

Erscheinungsjahr

2015

Veröffentlicht in

Exp. Fluids

Band/Volume

56/

Seite (von - bis)

196

We investigate the classic cylinder in crossflow case to test the effectiveness of a fast-response underwater temperature-sensitive paint coating (TSP) in providing highly resolved spatial and time observations of the action of a flow over a bluff body surface. The flow is investigated at Reynolds number <190 k, before the onset of the drag-crisis state. The obtained TSP image sequences convey an accurate description of the evolution of the main features in the fluid–cylinder interaction, like the separation line position, the pattern of the large coherent structures acting on the cylinder’s surface and the small-scale intermittent streamwise arrays of vortices. Ad hoc data management and features extraction techniques are proposed which allow extraction of quantitative data, such as separation line position and vortex-shedding frequency, and results are compared to the literature. Use of TSP for water applications introduces an interesting point of view about the fluid–body interactions by focusing directly on the effect of the flow on the model surface.