An embedded boundary method with smoothness guarantees and its impact on aerodynamic shape optimization with topological changes
Abstract/Contents
- Abstract
- Aerodynamic shape optimization using computational fluid dynamics (CFD) displaces the traditional aerodynamic design paradigm. Optimization algorithms automate the design generation process that is historically driven by engineering intuition, while CFD obviates the time-consuming and expensive construction of physical models. Embedded (or immersed) boundary methods (EBMs) for CFD are attractive for aerodynamic shape optimization problems characterized by large shape deformations and topology changes. They introduce a high degree of automation in the task of mesh generation and a significant flexibility in meshing complex geometries. Unfortunately, they suffer some disadvantages because they perform their computations on embedding, non body-fitted fluid meshes. In particular, they tend to generate discrete events that introduce discontinuities in the semi-discretization process and lead to unsmooth numerical solutions that are less than ideal for differentiation with respect to the evolution of a discrete, fluid/structure interface. This hinders the application of EBMs to the gradient-based solution of aerodynamic shape optimization problems. Discrete events also promote spurious oscillations in the post-processing of time-dependent results computed at the fluid/structure interface. This work addresses these issues in the context of FIVER, a comprehensive framework for developing EBMs for highly nonlinear, compressible, fluid/structure interaction (FSI) problems. It revisits the concept of the status of a node of an embedding fluid mesh and introduces that of a smoothness indicator nodal function, to eliminate discrete events and achieve smoothness in the semi-discretization process. It also introduces a moving least squares approach in the loads evaluation algorithm, to suppress spurious oscillations from integral quantities computed on the fluid/structure interface. Equipped with these enhancements, the newly created EBM FIVER$^{++}$ is shown to deliver, for three different applications, smooth, differentiable results. This work demonstrates the potential of shape-differentiable EBMs on several aerodynamic shape optimization problems. Most significantly, it showcases the optimization of a full configuration aircraft under turbulent flow, considering design spaces that involve deformations of the wing shape and airfoil section, as well as the placement of the nacelle-pylon on the wing.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2022; ©2022 |
| Publication date | 2022; 2022 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Ho, Jonathan Bing Hang |
|---|---|
| Degree supervisor | Farhat, Charbel |
| Thesis advisor | Farhat, Charbel |
| Thesis advisor | Alonso, Juan José, 1968- |
| Thesis advisor | Fedkiw, Ronald P, 1968- |
| Degree committee member | Alonso, Juan José, 1968- |
| Degree committee member | Fedkiw, Ronald P, 1968- |
| Associated with | Stanford University, Department of Aeronautics and Astronautics |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Jonathan Ho. |
|---|---|
| Note | Submitted to the Department of Aeronautics and Astronautics. |
| Thesis | Thesis Ph.D. Stanford University 2022. |
| Location | https://purl.stanford.edu/tw878pr4695 |
Access conditions
- Copyright
- © 2022 by Jonathan Bing Hang Ho
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