In this study, wind tunnel tests, i.e., pressure measurement tests and Particle Image Velocimetry (PIV) tests, were conducted on two rectangular cylinders with a side ratio of 5 in a parallel arrangement to investigate the effect of their relative distance on the flow field and the pressure distribution around them. Both results of the abovementioned tests indicate that the flow field of the upstream cylinder was like that of a single one and barely affected by the downstream one, while the separated shear layer of the downstream cylinder was promoted to reattach at its leading edge. The lift forces acting on the upstream and downstream cylinders showed the same frequency, while the phase lag between them varied with the distance.
