The stability of a quadruple vortex street, i.e. a pair of double vortex streets in a perfect fluid is investigated for small disturbances. Permanent configurations are first determined; two of which are then examined in their stability—one is a symmetric arrangement of a pair of staggered (Kármán-type) double streets and the other is an antisymmetric arrangement of the pair. The stability curves are obtained for several values of ratio of the distance 2b0 between the double streets to the spacing a between consecutive vorticies in a row. It is found that both types are neutrally stable for most of disturbances except unstable disturbances in very narrow ranges of a parameter specifying the disturbances mode, provided that b0/a≳0.5 and b/a is taken to be about 0.28, where b is the breadth of the double street. The symmetric type is more stable than the antisymmetric one.
ASJC Scopus subject areas
- Physics and Astronomy(all)