Biased flow after two square cylinders side-by-side
Ana Paula Ost1; Alexandre Vagtinski de Paula1; Sergio Viçosa Möller1
1 UFRGS
doi:10.20906/CPS/COB-2015-0442
Resumo
This work presents a study of a turbulent biased flow on two square cylinders side-by-side. The flow in this regime forms one narrow and one wide street, with two distinct frequencies and a gap that may switch randomly from one side to the other. Velocity time series are obtained with the constant temperature hot wire anemometry technique in an aerodynamic channel. The aspect ratios T/L chosen were 1.25, 1.50, 1.75 and 2.0, where "T" is the distance between the centers of adjacent cylinders and "L" is the cylinder height. The experimental data are analyzed by means of statistical and wavelet tools. The probability distribution function (PDF) of the axial velocity is also shown. The use of wavelet transform seems to be of great importance, since it makes possible a joint analysis in time and frequency domains allowing the detection of non-permanent flow structures. The results show that the gap switches occur in very small time intervals, thus presenting an unstable feature which cannot be detected in the frequency spectrum. A comparison is performed between the results obtained for the square cylinders and those of circular cylinders.
Palavras-chave: biased flow; wavelets; square cylinders; probability distribution function.