… main findings are that (i) the effect of suppression for flow-induced vibrations of two circular cylinders terrifically changes by the installing angle of the tripping rods on the cylinder surface, (ii) when the tripping rods are installed at 20 and 30 degrees from stagnation point, the flow-induced vibrations of the two cylinders are almost suppressed at which less than the critical spacing L/D=2.7, (iii) when the tripping rods are installed at the position beyond 40 degrees, the flow-induced vibrations of the two cylinders are considerably larger than …