مدل‌سازی عددی تاثیر موانع استوانه‌ای بر امواج ساحلی با استفاده از نرم‌افزار اپن فوم

یکی از تکنیک‌های حفاظت ساحلی استفاده از انواع موج‌شکن‌هاست. هدف این پژوهش بررسی اثر موج‌شکن‌های شمعی بر امواج ساحلی است. در این پژوهش با در نظر گرفتن موانع استوانه‌ای صلب در ساحل با شیب ثابت، به بررسی تاثیر زبری ناشی از آن‌ها بر الگوی جریان و امواج با مدل‌سازی عددی در نرم‌افزار openfoam پرداخته شد. روش مورداستفاده در مدل‌سازی جریان روش rans و مدل k ω,sst است. مدل‌سازی‌ها در دو حالت با و بدون حضور موانع برای 3 ارتفاع متفاوت موج ورودی انجام شد. موانع صلب استوانه‌ای دارای قطر 0.9 و ارتفاع 32 سانتی‌متر بوده و در طول و عرض 45 سانتی‌متر و فواصل 15×15 سانتی‌متر و با چیدمان زیگزاکی قراردادِه شدند. در هر سه ارتفاع موج، وجود موانع به میزان زیادی باعث استهلاک نیروی امواج نسبت به حالت بدون مانع شده است. با ارتفاع موج 6، 9 و 12 سانتی‌متر موانع به ترتیب 47.17 ، 68.68 و 76.42 درصد بیش‌تر از حالت بدون مانع نیروی موج را مستهلک کرده‌اند. با افزایش ارتفاع موج، موانع نیروی بیش‌تری را جذب کرده‌اند. در ارتفاع موج 12 سانتی‌متر موانع نسبت به ارتفاع موج 9 و 6 سانتی‌متر به ترتیب 32.35 و 72.45(نسبت بدون بعد نیرو) درصد نیروی بیش‌تری را جذب کرده‌اند. در بحث میرایی امواج در حالات با مانع نسبت به حالات بدون مانع، توانایی موانع در کاهش ارتفاع موج و میرایی آن به‌طور متوسط 20.88 درصد بوده است. نتایج حاصل با داده‌های آزمایشگاهی مقایسه شد. میزان نیروی جذب‌شده برای ارتفاع موج 6، 9 و 12 سانتی‌متر در مدل عددی به ترتیب 17.14، 4.23 و 7.86 درصد با مدل آزمایشگاهی اختلاف دارد، همچنین جذر میانگین مربعات خطای نرمال 0.07 و ضریب همبستگی 0.99 به دست آمد که بیانگر تطابق دو مدل عددی و آزمایشگاهی و عملکرد مناسب نرم‌افزار اپن فوم در مدل‌سازی است.

numerical modeling of the effect of cylindrical obstacles on coastal waves using openfoam

abstractone of the coastal protection techniques is the use of breakwaters. this study aims to investigate the effect of pile breakwaters on coastal waves. these breakwaters are similar to a porous structure. they are preferred over other impenetrable coastal structures due to their increased roughness and resistance to the current, their relatively low cost, economic savings, greater environmental compatibility, and preservation of natural landscapes. considering rigid cylindrical obstacles on the coast with constant slopes, the effect of their roughness on flow patterns and waves by numerical modeling in openfoam software was investigated. the method used in flow modeling is the rans method and k ω, sst model.modeling was performed in two modes with and without barriers for three different heights of wave. the results were compared with laboratory data. the absorbed force for wave height of 6, 9, and 12 cm in the numerical model was 17.14, 4.23, and 7.86 percent, respectively, with the laboratory model, also, the mean square root of normal error was 0.07, and the 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.keywords: coast protection, pile breakwater, wave energy,   introductioncoastal zones are dynamic ecosystems where land meets the sea, characterized by their variability due to natural factors and human activities. climate change has made these areas more susceptible to extreme weather events and natural disasters, such as storms and flooding. acknowledging the value of our shores, it is imperative to enhance our understanding of coastal engineering and to implement diverse and effective strategies for shoreline protection. employing breakwaters is one method of safeguarding our beaches. this research examined the impact of cylindrical obstacles on wave patterns through computational simulations conducted in the openfoam software. materials and methodsthe numerical model was set up and executed using open foam software. for this two phase flow issue, the interfoam solver, improved with the volume of the fluid method, was utilized for simulations. turbulence in the flow was represented using the reynolds averaged navier stokes (rans) equations and the k ω sstturbulence models. the model 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 a 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. results 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 absorb more force. at a wave height of 12 cm, obstacles to a 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 percentage of wave attenuation decreases with increasing wave height, and obstacles reduce a smaller percentage of water height the highest decrease in wave height was related to the wave height of 6 cm, and the lowest decrease was related to the wave height of 12 cm by 84.44% and 47.98%, respectively. the presence of obstacles in the path of wave movement causes a decrease in the speed of the wave and creates a separation zone behind the barriers. therefore, the wave passes through the protected area and enters the coastal area over a longer period. discussion and conclusionthe results were compared with laboratory data. the absorbed force for wave height of 6, 9, and 12 cm in the numerical model was 17.14, 4.23, and 7.86 percent, respectively, with the laboratory model, also, the mean square root of normal error was 0.07, and the 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. from the general comparison of the results, the creation of an area with rigid cylindrical barriers on the sea face of the coast helps to protect the coast from the advance of the waves and their flooding.