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ارزیابی عملکرد روش مرز مغروق در شبیه سازی عددی بر هم کنش سازه با سیال از نوع حرکات ناشی از گردابه در استوانه ها
نادری اسرمی، حجت Naderi Asrami, Hojjat
Evaluation of the Immersed Boundary Method in Fluid Structure Interaction Simulations of Vortex Induced Motions of Cylinders
Naderi Asrami, Hojjat | 2025
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- Type of Document: Ph.D. Dissertation
- Language: Farsi
- Document No: 58827 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Tabeshpour, Mohammad Reza
- Abstract:
- Numerical methods of computational fluid dynamics (CFD) extensively need computational resources, especially in the problems containing complex geometries and fluid structure interactions (FSI). Novel and advanced method of the immersed boundary (IBM) with its abilities in preprocessing is needless of conforming to the structures’ geometries and can be a solution for these kinds of problems. In FSI problems, where in each timestep a new preprocessing step is taken, the IBM can be very helpful. In this dissertation, using C++ coding language on object, function, class and library levels in the open-source and finite volume code of OpenFOAM solver, the IBM was used. Next, the IBM was implemented and studied on cylinders with complex geometries on all three levels of FSI which are fixed structures, one-way FSI and two-way FSI. A detailed and quantitative comparison between the performance of the IBM and conformal methods were also conducted in regards to meshing approaches. A new cutting approach on cell and side levels was developed for the IBM. Also, a library was developed for parallel solution of two degrees of freedom (2DOF) problems with the new cutting method. Finally, using Python coding language, the results of our CFD simulations and postprocessing were fed into novel decomposition methods of data for physics-aware data dimensionality reduction. We have found important results regarding different 2DOF VIV response branches by considering their vorticity contours at decomposed level. The results of the first detailed quantitative comparison between the IBM and the body-fitted method in a variety of complex geometries show high computational efficiency with acceptable accuracy for the IBM in FSI problems. With the help of the new library and the new cutting method, we accomplished to simulate two degrees of freedom vortex induced vibrations for the most complex cylindrical structure which is a helically-straked cylinder with high efficiency and desirable accuracy. Another important result is that the decomposed modes obtained from different methods show a similar pattern with a correlation of near one in non-dimensional form. In a variety of decomposed data, we found and mathematically described similar occurring patterns for the first time
- Keywords:
- Immersed Boundary Method (IBM) ; Fluid-Structure Interaction ; Complex Geometry ; Modal Decomposition ; Data Modal Decomposition ; Vortex Induced Motion
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