An embedded boundary approach for resolving the contribution of cable subsystems to fully coupled fluid‐structure interaction

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Embedded boundary methods (EBMs) are robust solution methods for highly nonlinear fluid-structure interaction (FSI) problems. They suffer, however, some disadvantages because they perform their computations on embedding, nonbody-fitted fluid meshes. In particular, they tend to generate discrete events that introduce discontinuities in the semi-discretization process and lead to numerical solutions that are insufficiently smooth for differentiation with respect to the evolution of a discrete, fluid/structure interface Γ F∕S h . This hinders their application to the gradient-based solution of fluid-structure optimization problems. Discrete events also promote spurious oscillations in the post-processing of time-dependent results computed at Γ F∕S h .z This paper addresses these issues in the context of Finite Volume method with Exact two-material Riemann problems (FIVER), a comprehensive framework for developing EBMs for highly nonlinear, compressible, 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 Γ F∕S h . Equipped with these enhancements, FIVER is shown to deliver, for three different FSI applications, smooth results that are differentiable with respect to evolutions of Γ F∕S h .

Section: F∕s Hmentioning

confidence: 99%

Section: Fiver Ebms For Cfd and Fsimentioning

confidence: 99%

Discrete embedded boundary method with smooth dependence on the evolution of a fluid‐structure interface

Farhat

2020

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“…Finally, the proposed computational homogenization framework is equipped with the previously trained NN‐ReLU models and applied here to simulate the supersonic inflation dynamics of a NASA DGB parachute system in the low‐density, low‐pressure, supersonic Martian atmosphere 32‐34 . While such a coupled, multiscale, fluid–structure simulation is crucial to the understanding of the effects of a woven fabric material on the performance of a parachute during the deceleration process, its main purpose here is twofold: (1) demonstrate the computational tractability of the proposed computational framework for a realistic application; and (2) to validate (partially) it using flight data from the landing on Mars of NASA's rover Curiosity.…”

Section: Applicationsmentioning

confidence: 99%

“…Given the expected large motions and deformations of the parachute system during its inflation, the flow computations are performed using the large eddy simulation capability of the AERO‐F flow solver 23,24 and its embedded boundary method for fluid–structure interaction known as the finite volume method with exact two‐material Riemann problems 33,38‐42 . AERO‐F incorporates a parallel adaptive mesh refinement (AMR) capability based on newest vertex bisection, 43,44 which enables it to capture various interactions between the fluid system, the nonlinear parachute system including its suspension lines and the forebody.…”

Section: Applicationsmentioning

confidence: 99%

A computationally tractable framework for nonlinear dynamic multiscale modeling of membrane woven fabrics

Avery

Huang

et al. 2021

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A general‐purpose computational homogenization framework is proposed for the nonlinear dynamic analysis of membranes exhibiting complex microscale and/or mesoscale heterogeneity characterized by in‐plane periodicity that cannot be effectively treated by a conventional method, such as woven fabrics. The framework is a generalization of the “finite element squared” (or FE2) method in which a localized portion of the periodic subscale structure is modeled using finite elements. The numerical solution of displacement driven problems involving this model can be adapted to the context of membranes by a variant of the Klinkel–Govindjee method1 originally proposed for using finite strain, three‐dimensional material models in beam and shell elements. This approach relies on numerical enforcement of the plane stress constraint and is enabled by the principle of frame invariance. Computational tractability is achieved by introducing a regression‐based surrogate model informed by a physics‐inspired training regimen in which FE2 is utilized to simulate a variety of numerical experiments including uniaxial, biaxial and shear straining of a material coupon. Several alternative surrogate models are evaluated including an artificial neural network. The framework is demonstrated and validated for a realistic Mars landing application involving supersonic inflation of a parachute canopy made of woven fabric.

“…9 Huang et al present a special immersed-FSI approach for solid subsystems of co-dimension two, such as cables, booms and risers. 10 The tremendous recent progress in computational FSI has also enabled the use of FSI simulations in multi-disciplinary control, design, optimization and inversion problems. Such control and optimization problems pose severe conditions on the stability and consistency of the FSI formulation, as well as on the efficiency of the computational procedure.…”

mentioning

confidence: 99%

Vanguard developments in computational methods for fluid‐structure interaction

Brummelen

Farhat

2021

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The analytical approach, which lies at the basis of the exact and natural sciences, rests on the notion that complex systems can be reduced to simple components. This divide-and-conquer approach has shaped contemporary science and technology, and has formed the foundation for virtually all scientific breakthroughs in the 19th and 20th century. It is also the origin of the separation of mechanics into fluid and solid mechanics, so much so that these branches of mechanics are commonly considered as distinct scientific disciplines. Notably, the disconnection between fluid and solid mechanics is evidenced by the tremendous advancements in computational methods and commercial simulation codes for fluid-and solid-mechanical systems separately, as compared to the relative underdevelopment of commercial codes for fluid-structure-interaction analyses.With the advancement of analysis capabilities for fluid-and structure-mechanics systems separately, emerged the realization that many problems in science and engineering cannot be appropriately categorized as either a fluid or structure problem, but are fundamentally determined by the interaction of a fluid and a solid. Examples are flutter and buffet instabilities in aerospace and civil engineering, the functioning of heart valves in biomechanics, sloshing and vibrations in flexible fluid containers and fluid conduits, deployment of inflatable structures such as airbeams and airbags, and deformation of soft substrates due to capillary forces, for example, in microfluidic applications and biomechanics. The development of computational methods for fluid-structure-interaction problems commenced in the early 1980s and many important foundations were laid in the 1990s. Despite the significant progress that has been made since then in computational models and methods for Fluid-Structure Interaction (FSI), many open challenges still remain, and computational FSI continues to be an active area of investigation and development.This special issue presents an overview of vanguard developments in computational methods for fluid-structure interaction. The 12 manuscripts in this special issue cover a variety of contemporary topics in computational FSI.The development of efficient and robust partitioned solution methods continues to be an important branch of research in computational FSI. Such partitioned solution methods allow to retain the modularity of the fluid and structure subsystems, thus enabling the reuse of the complete gamut of advanced commercial and open-source simulation software for fluid-dynamics and solid-dynamics problems separately. In this special issue, Cao et al. present a spatially-varying Robin coupling condition to mitigate the added-mass effect of incompressible flows in FSI in partitioned solution procedures. 1 In a similar vein, Dettmer et al. present a new combined two-field relaxation strategy to enhance the stability of the standard Dirichlet-Neumann FSI coupling strategy in the presence of strong added-mass effects. 2 The work by Rüth et al. is concerned wit...