مهندسی عمران شریف (Feb 2021)
NUMERICAL MODELING OF INTERACTION BETWEEN MARINE WAVES AND INFLATABLE MARINE STRUCTURES
Abstract
Inflatable marine structures are flexible cylindrical structures attached to a rigid base. These structures are generally cylindrical tubes, made of rubberized material, and inflated by air and/or water. Although these structures are permanently inflated, they have the advantage of being deflated and lie flat when not needed and then, inflated in a short period when required. They are relatively easy to install, do not corrode, require little maintenance, and have the capability to withstand extreme temperatures. Due to elasticity of the structure and continuous variation of its shape during operation, inflatable breakwater or sea-wall structural and hydraulic analyses are more complicated than the rigid types. Large deformation of the membrane due to the internal and external loads makes the governing equations of such problems non-linear and complex. In the present study, the behavior of an inflatable marine structure under loading by marine waves was simulated based on 2D numerical modeling. For this purpose, the deformed equilibrium geometry of the breakwater was calculated by solving the prevailing equations through the linear dynamic response of the system. The central difference method was employed to solve the governing equations of the linear dynamic response of the system of finite elements. According to the results of former studies, for 2D modeling of the aforementioned problem, the length of the tube was assumed infinity. Therefore, the effects of lateral supports and boundary conditions were neglected. This study carried out the numerical analysis of the inflatable marine structures for solving the flow-based problem associated with static and dynamic structural analyses. For this purpose, the two-dimensional fluid-structure interactions were analyzed numerically. It was shown that the equilibrium shape of the structure was a function of rubber thickness, elasticity modulus of the material, internal pressure, the dam foot width, and external loads. All the influential parameters of both flow and structure including internal pressure, water depth, wave height, wave period, etc. were attained based on the dimensional analysis. Accordingly, the results describing height and cross-sectional profile of the inflatable tubes loaded by marine waves were obtained.
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