Abstract
In the previous papers, we measured pressure distributions, lift and drag forces and Strouhal numbers of two rectangular cylinders arranged side-by-side in a wind tunnels. Then, we observed flow-patterns around two cylinders by the aid of the visualization technique of a smoke-wire, changing the shape of a cross-section of models (B/H) and a gap distance (S/H) between two models. It can be clarified that a change of flow-patterns corresponds to one of aerodynamic forces measured. It was found that there occurs a biassed flow under the critical gap distance, and that bi-stable flow-patterns of the biassed and the non-biassed flows alternately appear just at the critical gap distance.
