Numerical Simulation Of The Influence Of Artificial Reef Opening Factors On Flow Field Effect

Artificial reef is one of the important unit of marine ranching.The research of artificial reefs will guide the design and layout of the marine ranching.Cut-opening on reef is the common choice of reef design.At present,there are amounts of researches had shown that the cut-opening design have significant influence on the flow field effect.However,the researches on reef opening are still inadequate,and most of them only focus on the opening ratio of artificial reefs.There are few researches on other opening factors of reef,especially the research on the interaction mechanism between various opening factors.In this study,the orthogonal experimental design method was used to study the influence of various opening factors at the same time,and the opening ratio,opening pattern,opening interval,and opening shape of the reef was studied to identify the design scheme with the best flow field effect.Then,this study also studied the influence of opening factors in different angle of incident flow,and discussed whether the influence laws of opening factors are different under different angle of incident flow.The conclusions are as follows:(1)Among the four opening factors,the opening ratio and opening shape have significant influence on the upwelling of artificial reef,while the opening pattern and opening interval have no significant influence.(2)There is no significant interaction between the four opening factors when the relative index is taken as the evaluation index.When the effect index is used as the evaluation index,there is an interaction between the four opening factors,and the opening scheme should be determined by different opening shapes.(3)In the evaluation of the relative index,the best flow field effect can be obtained when the hexagonal opening holes on the front,circular opening holes on the side.The best opening ratio is close to 0.1.A-type opening is the optimal opening pattern.The best opening interval distance between the two openings is 1.5.The above conclusions can provide a basis for the design of the opening scheme,when the scale of the reef is determined.(4)In the evaluation of efficiency index,the reef with hexagonal opening holes on the front and back,circular opening holes on the left and right side,OR of 0.3,OP of A-type and OI of 1.6,has the best flow field effect.(5)when the angle of incident flow is 45°,the upwelling effect produced by the reef is the best,and the angle of incident flow will significantly affect the effect of cut-opening on upwelling.Therefore,different cut-opening schemes should be considered at different flow directions.(6)If the comprehensive flow field effect of the reef at multiple flow directions is considered for structural optimization,the following design scheme can be generated:When the relative index is taken as the evaluation index,the reef with a circular or regular hexagonal opening ratio of 0.05 has the best comprehensive flow field effect at multiple flow directions.With the effect index as the evaluation index,the reef with the opening ratio of 0.4 and the opening shape of hexagon can produce the best effects at multiple flow directions.