Modelagem matemática e computacional de interação fluido-estrutura utilizando elementos sólidos com aplicação na indústria

Abstract

Fluid-Structure Interaction (FSI) problems are found in a wide range of fields, including biology, medicine, and general engineering. The FSI phenomenon, as the name suggests, occurs when there is an interaction between fluid flows and one or more structures. In this work, an evaluation of FSI is performed on flexible structures subjected to both compressible and incompressible flows. Using the multiphysics simulator, MFSim, a computational tool developed by the Fluid Mechanics Laboratory (MFLab), it is possible to perform computational simulations of fluid-structure interaction. MFSim uses a partitioned approach, which means that the fluid and the structure are solved independently and coupled at each time step, allowing the combination of efficient methods for each subsystem to be resolved. For the fluid case, the Finite Volume Method (FVM) is used, while for the structure, the Finite Element Method (FEM) is employed. The Immersed Boundary Method (IBM) is also used, which is responsible for modeling the fluid-solid interface. This method allows the calculation of fluid-dynamic forces exerted by the fluid due to the presence of immersed bodies. In the presented study cases, 8-node hexahedral elements with additional interpolation functions were used. The scope of this thesis was to analyze the fluid-structure interaction problem of a pipeline that is part of the Fluid Catalytic Cracking Unit (FCCU) at Petrobras' REPLAN refinery. For the FSI analysis of the proposed problem, a Newtonian fluid with compressible flow and varying physical properties was considered, and a weak coupling between the fluid and structure subsystems was used for this specific case. To carry out the computational simulation of the proposed problem, a block-structured Cartesian mesh with adaptive refinement, LES methodology, and Smagorinsky as the turbulence closure model were employed. For the FSI validation cases, a strong coupling between subsystems was used. The results showed that the region susceptible to the greatest vibrations is where the Main valve is located, with the highest magnitude of average displacement found upstream of the Main valve when it is closed at 44° and the Slide valve is open at 83%. Throughout the work, physical, differential mathematical, and computational mathematical modeling of the proposed problem are presented, as well as the results for validation and industrial application cases.