Abstract. In the context of CFD and fluid-structure interaction (FSI), embedded boundary methods (EBMs) are Eulerian methods that operate on non body-fitted fluid meshes in which discrete representations of obstacle surfaces are embedded. They are attractive for numerous reasons. They introduce such a high degree of automation in the discretization of complex computational fluid domains that they can almost be considered mesh free methods. They are also the most robust solution methods for flow problems past obstacles that undergo large motions, deformations, shape changes, and/or topological changes. Such problems arise in FSI and multidisciplinary design, analysis and optimization (MDAO). However, EBMs typically generate discrete events that are sources of roughness and spurious oscillations in the flow results computed at an embedded, discrete, boundary surface or in its vicinity. At best, such numerical flaws are sufficiently small not to affect the quality of the computations. However, they inhibit differentiation with respect to any evolution of the embedded surface. Therefore, they hinder the application of EBMs to the gradient-based solution of MDAO problems, where they are however pressingly needed to avoid remeshing and the pitfalls of transferring numerical results from one CFD mesh to another. For this reason, this lecture will present a new approach for constructing discrete-event-free EBMs based on a new concept of a nodal status, that of a smoothness indicator nodal function, and a moving least squares approach for suppressing spurious oscillations from integral quantities computed on an embedded discrete interface. The enabling capabilities of the proposed approach will be demonstrated for complex FSI and MDAO applications ranging from the simulation of challenging extrusion processes to the MDAO of modern flying wings.

Biography. Charbel Farhat is the Vivian Church Hoff Professor of Aircraft Structures, Chairman of the Department of Aeronautics and Astronautics, and Director of the Stanford-KACST Center of Excellence for Aeronautics and Astronautics at Stanford University. His research interests are in computational engineering sciences for the design and analysis of complex systems in aerospace, mechanical, and naval engineering. He is a Member of the National Academy of Engineering, a Member of the Royal Academy of Engineering (UK), a Member of the Lebanese Academy of Sciences, a Doctor Honoris Causa from Ecole Centrale de Nantes, a Doctor Honoris Causa from Ecole Normale Supérieure Paris-Saclay, a designated ISI Highly Cited Author, and a Fellow of AIAA, ASME, IACM, SIAM, USACM, and WIF. He has trained more than 90 PhD and post-doctoral students. For his research on aeroelasticity, aeroacoustic scattering, CFD, digital twins, dynamic data-driven systems, fluid-structure interaction, high performance computing, and model reduction, he has received many professional and academic distinctions including: the Ashley Award for Aeroelasticity and the Structures, Structural Dynamics and Materials Award from AIAA; the Lifetime Achievement Award and the Spirit of St Louis Medal from ASME; the Gordon Bell Prize and the Sidney Fernbach Award from IEEE; the Gauss-Newton Medal from IACM; the Grand Prize from the Japan Society for Computational Engineering Science; and the John von Neumann Medal from USACM. He was knighted in France in the Order of Academic Palms, awarded the Medal of Chevalier dans l’Ordre des Palmes Académiques, selected by the US Navy recruiters as a Primary Key-Influencer and flown by the Blue Angels.