Title: THE LOW FROUDE NUMBER WAKE OF FLOATING BLUFF OBJECTS
Abstract: It is shown that the low Froude number wake of floating two- dimensional objects is convectively unstable. This is shown to be true for bluff objects, like a circular cylinder, and for streamlined objects, like a thin airfoil. As a result, the wake behind a floating object remains steady, even at high Reynolds numbers, characterized by a long region of recirculating flow. The theoretically derived conclusion is verified experimentally for the wake of a half-submerged circular cylinder at high Reynolds numbers. Visualization of the flow using bubbles confirms the presence behind the cylinder of a steady recirculating flow region, reminiscent of the wakes behind bluff objects in infinite fluid at very low Reynolds numbers. It is concluded that the presence of the free surface has a stabilizing effect at low Froude numbers, suppressing the unsteadiness of the wake. Finally, the structure of the dispersion relation shows the possibility of a short wave-length interaction between the wake instability and ambient waves, which results in spatially growing modes.
Publication Year: 1989
Publication Date: 1989-01-01
Language: en
Type: article
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Cited By Count: 7
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