An investigation of the dynamic behaviour of two rigid cylinders in a tandem arrangement under vortex-induced vibration

•The rigid cylinders’ responses with both cylinders were free to move in the cross-flow direction, demonstrated a continuous increase as the reduced velocity increased.•The leading cylinder provided a shielding effect for the trailing cylinder, which prevented the trailing cylinder from vibrating excessively.•The existence of a bistable regime causes a vigorous vibration of the leading cylinder at S/D = 3.5.•The flow interference between the cylinders contributes to a drastic change and worsens the structure's vibration compared to the single cylinder.