Document Type : Original Manuscript
Authors
1 Department of Water Engineering, , Shahrekord University
2 Water science department, Shahrekord university
3 Department of Water Engineering
4 Department of Mechanic, Zanjan University
Abstract
One of the coastal protection techniques is the use of breakwaters. The aim of this study is to investigate the effect of pile breakwaters on coastal waves, considering rigid cylindrical obstacles on the coastal with constant slope, the effect of their roughness on flow pattern and waves by numerical modeling in OpenFOAM software was investigated. The method used in flow modeling is RANS method and k-ω, SST model. Modeling was performed in two modes with and without barriers for three different heights of wave. Rigid cylindrical obstacles had a diameter of 0.9 cm and a height of 32 cm. They were contracted at length and width of 45×45 cm and distances of 15×15 cm, with staggered layout. In all three wave heights, the presence of obstacles greatly causes the force of waves to dissipate relative to the unobstructed state. With wave heights of 6, 9 and 12 cm, the obstacles dissipated 47.17, 68.68 and 76.42 percent more than the unobstructed state of wave force, respectively. As the wave height increases, the obstacles have absorbed more force. At wave height of 12 cm, obstacles to wave height of 9 and 6 cm, respectively, 32.35 and 72.45 (compared to no force dimension) absorbed more power. In the discussion of wave mortality in obstacle scenarios compared to unobstructed scenarios, the ability of obstacles to reduce wave height and its mortality averaged 20.88%. The results were compared with laboratory data. The absorbed force for wave height of 6, 9 and 12 cm in numerical model was 17.14, 4.23 and 7.86 percent, respectively, with laboratory model, Also, the mean square root of normal error was 0.07 and correlation coefficient was 0.99, which indicates the conformity of two numerical and laboratory models and the appropriate performance of Open FOAM software in modeling.
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