A STUDY OF FORCES, CIRCULATION AND VORTEX PATTERNS AROUND A CIRCULAR CYLINDER IN OSCILLATING FLOW

摘要: Measurements of sectional and total forces the spanwise correlation vortex shedding are presented for a circular cylinder in planar oscillatory flow at Keulegan-Carpenter numbers, KC , range from about 4 to 55. The viscous parameter β is around 100 1665. Circulation measurements circuit close enclosing cylinder, also presented. A mode-averaging technique was used both circulation this gave, typical modes shedding, time histories over an average cycle. transverse force tend fluctuate sympathy with each other, except instant reversal when changes sign but remains high. Values strength shed vortices, estimated measured circulation, found be comparable steady-flow results. For [lsim ] 30, occur distinct ranges high centre -range particular mode low boundaries. Above ≈ 30 no longer very sensitive length equal 4.65 diameters. In vortex-street regime (8 15) experience steady force, coefficient which 0.5 = 14.