Experimental study of wave interactions between cylindrical pile model and vertical steel wall

• Main Author: Lian, Dennis Wen Yao.
• Other Authors: Huang Zhenhua
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Environmental engineering::Environmental protection
• Online Access: http://hdl.handle.net/10356/53838
• Institution: Nanyang Technological University

Breakwaters are typically deployed along coastal areas to protect small harbours or for shoreline erosion control. In recent years there has been an interest in flexible structures as breakwaters due to the elimination of problems associated with permanent structures such as the formation of tombolos and the retardation of beach recharging (Stamos, et al., 2002). In spite of the large amount of studies on floating breakwaters, there is a lack of research on cylindrical breakwaters that are fixed vertically on the seabed. In this experimental study, we describe a laboratory investigation using 4 cylindrical breakwater piles placed in an array along the cross sectional face of a 35m x 0.55m x 0.6m hydraulic flume. The cylindrical piles are fixed on the base of the hydraulic flume to prevent horizontal motion along with the wave motions. In addition, a vertical metal wall will be placed 3metres away from the piles to simulate a vertical coastal wall. Based on Linear Wave Theory, the hydrodynamic interaction of the cylindrical piles with the generated waves will be examined to evaluate the reflection and transmission coefficients as a function of different periods, wave heights and water depths. Overall, this study on the wave interaction between a breakwater pile model and a vertical steel wall shows that the new design for this model is still considerably effective for wave protection. Due to the presence of the vertical steel wall in place of the inclined absorbing beach, complex wave interactions have shown that at wave periods of 1.1s and 1.4s and shorter wave heights of 2cm to 4cm wave transmission is extremely high. Due to the drawback of the design of this experiment with a vertical steel wall , we are unable to apply the theories of long-crested 2-D waves as we did not foresee the implications of short-crested 3-D waves. As a result, the positioning of the wave gauges and the seawall is very important due to the amplification effect and stability of short-crested 3-D waves. This may result in transmission coefficients exceeding 1. There remains much to be improved for this study by increasing the range of parameters to be tested and examined. In addition, these piles can also be modified with devices for converting ocean wave energy to electrical energy to harness this form of renewable energy.