Experimental investigation for characteristics of wave impact loads on a vertical cylinder in breaking waves

In this study, a series of model tests was conducted to investigate the characteristics of wave impact loads and the associated air bubble effects on a vertical circular cylinder with various pressure and force sensors installed in a 2D wave flume. Spilling and plunging waves, generated by the focusing wave method, induced wave impact loads on the cylinder, and these loads were measured by the sensors, which had different natural frequencies and sensing areas. Each test condition was repeated 20 times to verify the repeatability of the impact loads and their effects. The air bubble effects were investigated by analyzing the time histories of the impact forces and pressures, and the effects were related to the natural frequency and sensing area of the sensors. The air bubble effects were observed to increase as the breaking wave developed more at the position of the cylinder. The generated waves and impact loads were also observed to change significantly when even a small noise occurred in the displacement of the wavemaker. •The experiment was done to see the air bubble effects on wave impact load using various pressure and force sensors.•Breaking waves were generated and each wave condition was repeated to verify the repeatability of the impact loads.•Impact loads can be classified into three types: strong air bubble effect, weak air bubble effect and very weak effect.•The effect of the air bubbles than can be measured depends on the natural frequency and the sensing area of the sensor.•Even small changes in the wavemaker's displacement can significantly change the impact loads.