Infinite Elements for Two-Dimensional Fluid-Structure Interaction Problems,
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD
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This report describes an effective method for using two-dimensional infinite elements to compute acoustic or magnetic fields in the unbounded fluid region surrounding a submerged vehicle. In this method, finite elements represent the bounded region containing the vehicle and may also be used to represent a layer of fluid surrounding the vehicle. Infinite elements are used to represent the unbounded exterior region. Since infinite elements are not bounded, their shape functions are chosen to contain decay factors to produce convergent integrals. If, from physical or other considerations, the order of decay of the solution as the radius increases is known, infinite elements should be chosen with the same order of decay. The results obtained in this study were found to be within 2 when the decay factor of infinite elements matched that of the solution. However, for other problems, the order of decay of the solution may not be known in advance, and, therefore, it may not be possible to match the two rates of decay. For such cases, the errors were found to be as large as 20. In such situations, a layer of finite fluid elements, two elements thick around the structure, reduced the errors to less than 3.5 for the modes and decay factors tested, Keywords Fluid structure interactions.
- Submarine Engineering
- Electricity and Magnetism