Wave Elimination Performance Study On Air Bubbles Breakwater Under The Condition Of Wave And Current Coupling Effect

Breakwater is a kind of coastal engineering structures, which aims to provide protection for coastal activities from waves, and it also plays a special and important role in mainly for providing stable and safe area to ship and protect the port from the bad external environment. Air bubbles breakwater is one of special breakwaters, it has several specific characters of the mobile breakwater compared with the traditional breakwaters, such as mobility, cheapness, etc. It can not be restricted by the water depth and geological conditions. In addition, air bubbles breakwater has other advantages, is a light and simple structure. Its initial investment, the construction cost and operation cost is lower. And water depth is not a big problem. When the water is deep, small wave elimination of the cycle, and working in a short period of time, using the air bubbles breakwater is reasonable method. As a result, air bubbles breakwater has good application prospects in water transportation, aquaculture and military domain.In order to research the wave elimination performance of the air bubbles breakwater system deeply, the mathematical model and physical experiment model were established in this paper. Based on the assumption that the mixture of air and water is regarded as a variable density fluid. The continuity equation and N-S equation are adopted as the governing equations, and VOF method is used to track the two-phase interface. The horizontal current was produced by setting the water inlet and outlet at the bottom of wave tank, respectively. The air bubbles are also produced by using UDF in the wave tank. The wave is generated by pushing plate at the front of wave tank, and wave elimination was done by using UDF at the end of wave tank. Then the 2-D mathematical model of air bubbles breakwater is established. Then, the mathematical model was used to calculate the wave elimination parameters for the static water conditions, pure wave and the condition of wave and current coupling.The related conclusions are given as follows:Firstly, the results show that the reason of air bubbles breakwater wave elimination is largely due to the effect of air curtain in the water. When the current approaches the water surface, it can destroy the original trajectory of water particles. The wave breaks, and wave energy attenuates, resulting in the decrease of wave.Secondly, wave transmission coefficient increases with decreasing gas flow rate and submerged depth of pipe, respectively. With the increase of incident wave period and wave height, wave transmission coefficient increases, respectively.Lastly, when the positive (or the reverse) of average current velocity closes to a smaller value, the wave elimination performance of the air bubbles breakwater is the best.The research results can provide a practical application of air bubbles breakwater with a reliable and valuable reference.