A numerical investigation on galloping of an inclined square cylinder in a smooth flow

The phenomenon of inclined square cylinder galloping in a smooth flow is studied numerically using three-dimensional aeroelastic simulations. In keeping with the published experimental data, simulations are conducted at a reduced velocity of 16. The galloping oscillations found in experiments are successfully reproduced. The aerodynamic moments exerted on inclined cylinders are discussed in detail. It is confirmed that Karman vortex shedding has no impact on the galloping oscillation of an inclined cylinder. The hysteresis loop of the aerodynamic moment is found to differ for forward and backward cylinder inclinations. Further study reveals the shape evolution of the hysteresis loop when the cylinder is in forced simple harmonic motion with a varying amplitude. The preliminary results of this investigation show that a cylinder inclined backward gains energy from the flow more easily than a cylinder inclined forward, resulting in a larger galloping amplitude for the former cylinder. This helps to explain published experimental results.