Axial-flow-induced vibration (AFIV) of cylindrical structures is frequently encountered in engineering applications. For example, fuel rods in a nuclear reactor may experience lateral vibration resulting from the high momentum, unsteady and axial-flowing coolant. Consequently, the rods may collide with each other and eventually lead to the fuel-rods damage. It is crucially important to reveal the characteristics of vibration and surrounding flow of fuel rods. Computationally and experimentally investigations have been conducted on the turbulent intensity *Tu* effect on the AFIV of an elastic cylinder or cylinder cluster, with a view to provide an insight into the underlying physics of fluid-structure interaction.

**Computational Results: **temporal evolutions of the vibration amplitude of an isolated elastic cylinder at different *Tu*. (a) dimensionless flow velocity *u* *= 3.49 and (b) *u** = 7.92.

**Computational Results:** contours of instantaneous vorticity *ωz** with velocity vectors around an isolated elastic cylinder, (a-d) at longitudinal position *z** = 10, (e) *z* *= 6 and (f) *z** = 14. The normalized time* t* *of subplots (a-d) corresponds to the instants before the buckled state (a,b) and at the buckled state (b,e,f) or during the flutter motion (d); the dashed line denotes the original position of the cylinder. (*u** = 7.92). The circles 1 and 2 denote the position of the streamwise vortices around the cylinder.

**Experimental results:** contours of typical instantaneous vorticity* ωz* *between two cylinders at high *Tu* (2.30%-2.91%); (a) Normalized center-to-center cylinder spacing *P** = 1.36, *u** = 5.23; (b) *P** = 1.36, *u** = 2.75; (c)* P** = 1.57, *u* *= 5.23; (d) movement of eddy-structure (Mode III-a and III-b).