When a vertical pile is exposed to waves, several forces come into play in the direction of wave propagation. These forces include:
Wave Pressure: Wave pressure is the force exerted by the water particles due to the wave motion. As waves approach a vertical pile, they exert pressure on the pile's surface. This pressure varies with the wave height, wave steepness, and the density of the water. The pressure difference between the front and back of the pile generates a net force that affects the pile.
Inertia Force: The inertia force is associated with the mass and acceleration of the water particles. As waves approach the pile, water particles move back and forth in a cyclical motion. This motion creates inertia, and the resulting force opposes the motion of the particles. The inertia force acts in the direction opposite to the wave propagation and influences the behavior of the pile.
Drag Force: The drag force is caused by the interaction between the pile and the moving water. As waves travel past the pile, water flows around the pile, creating frictional forces. These forces depend on factors such as the pile shape, water velocity, and roughness of the pile surface. The drag force acts in the direction opposite to the wave motion and affects the pile's stability.
Lift Force: The lift force arises due to the pressure difference on the front and back surfaces of the pile caused by the wave motion. This pressure difference can create a lift force perpendicular to the direction of wave propagation. The lift force can induce lateral vibrations or oscillations in the pile.
Wave Reflection and Diffraction: When waves encounter the vertical pile, they can reflect or diffract around it. Wave reflection occurs when waves bounce off the pile's surface, exerting additional forces on the pile. Diffraction refers to the bending or spreading out of waves as they pass around the pile, resulting in variations in the forces acting on the pile.
These forces are influenced by factors such as wave characteristics (wave height, period, wavelength), pile geometry, water depth, and the properties of the pile material. Understanding and analyzing these forces is crucial in designing structures that can withstand the effects of wave action and ensuring the stability and integrity of coastal and offshore structures.