Laboratory investigation of the flow field and surface wave energy reduction using White Light and PIV technique has been investigated in this Thesis.For this purpose, a plunger wave maker designed and built and the effect of geometrical parameters of wave maker on the surface wave was investigated.In the next step, an immersed plate is used to defeat and reduce the surface wave energy.The wave maker mechanism of stainless steel 304 with distinct mechanisms have been designed to provide sinusoidal motion.The wave maker capable of producing waves alternating with specified characteristics.The parameters affecting the wave, namely the depth of water, the frequency of the wave maker, Immersion depth and the total amplitude of the oscillation can all be controlled and varied.In the first step of the study, the effect of these parameters on the production of the waves has been studied.Accordingly increasing the immersed depth and the total amplitude of the oscillation in the low frequencies will increase the wavelength and at high frequencies will increase the wave height. Also, increasing the immersed depth at a low depth of water will reduce the height of the wave.After analyzing the behavior and measured wave height, wavelength and wave speed empirical equations for predicting wave height, wavelength and wave speed is provided.These relationships are based on the four main parameters in describing the wave maker motion that were previously introduced. In the second step, a rectangular obstacle has been used over the wave path to dissipate and reduce the surface wave height.The results of this section are useful in the design of coastal breakwaters.To analyze the results, three non-dimensional number of wave transmission coefficients, the reflect wave coefficient, and the dissipation coefficient of the wave are defined.ased on the obtained results, when the barrier has a 90-degree angle with the water surface, the height of the transmitted wave reaches the lowest and the reflected wave height reaches to maximum value. When the ratio of the plate's thickness to the depth of water is 0.02, with change in angle of the barrier from 0 to 90 degrees, the wave transmission coefficient is reduced by 25%.Also, increasing the thickness of the barrier causes an increase in the dissipation coefficient of the wave. By changing the thickness ratio of the plate to water depth from 0.02 to 0.12, this coefficient increases by 18%. Increasing the length of the barrier gives the greatest effect on the surface wave. When the ratio of the length of the barrier to the wavelength is changed from 0.19 to 0.58, the dissipation wave coefficient and the reflection coefficient increase by 31% and 19%, respectively. In the meantime, the reduction of 78% in transmitted coefficient wave is the most important effect of increasing the length of the barrier . Key Words: Plunger wave maker, Immersion plate, Breakwater, Wave dissipation coefficient
