Vanguard developments in computational methods for fluid‐structure interaction

The analytical approach, which lies at the basis of exact and natural sciences, rests on notion that complex systems can be reduced to simple components. This divide-and-conquer approach has shaped contemporary science technology, formed foundation for virtually all scientific breakthroughs in 19th 20th century. It is also origin separation mechanics into fluid solid mechanics, so much these branches are commonly considered as distinct disciplines. Notably, disconnection between evidenced by tremendous advancements computational methods commercial simulation codes fluid- solid-mechanical separately, compared relative underdevelopment fluid-structure-interaction analyses. With advancement analysis capabilities structure-mechanics emerged realization many problems engineering cannot appropriately categorized either a or structure problem, but fundamentally determined interaction solid. Examples flutter buffet instabilities aerospace civil engineering, functioning heart valves biomechanics, sloshing vibrations flexible containers conduits, deployment inflatable structures such airbeams airbags, deformation soft substrates due capillary forces, example, microfluidic applications biomechanics. development commenced early 1980s important foundations were laid 1990s. Despite significant progress been made since then models Fluid-Structure Interaction (FSI), open challenges still remain, FSI continues an active area investigation development. special issue presents overview vanguard developments fluid-structure interaction. 12 manuscripts this cover variety topics FSI. efficient robust partitioned solution branch research Such allow retain modularity subsystems, thus enabling reuse complete gamut advanced open-source software fluid-dynamics solid-dynamics separately. In issue, Cao et al. present spatially-varying Robin coupling condition mitigate added-mass effect incompressible flows procedures.1 similar vein, Dettmer new combined two-field relaxation strategy enhance stability standard Dirichlet–Neumann presence strong effects.2 work Rüth concerned with quasi-Newton waveform techniques enable iterative strategies supporting multi-rate approximations (or subcycling), implementation preCICE.3 Another interaction, pertains conjunction auxiliary physical subsystems. A main class type, fluid-structure-contact-interaction (FSCI) problems, is, subsystem exhibits (self-)contact. fundamental challenge FSCI domain generally topological change contact. Hiromi-Spühler Hoffman unified continuum model full-friction contact application aortic valves.4 As opposed moving-mesh Hoffman, manuscript Ager immersed (CutFEM) formulation, continuous transition from no-slip frictionless enabled means generalized Navier boundary variable slip coefficient.5 second interactions, free-boundary flows, itself free surface interface effects meniscus play crucial role behavior referred elasto-capillarity or, case comprised two species separated interface, binary-fluid–structure (BFSI). An essential complication elasto-capillary modeling line, triple point corresponding intersection interface. Ohayon formulation acoustic elastic container.6 van Brummelen adaptive framework fluid–fluid modeled diffuse via Navier–Stokes–Cahn–Hilliard equations, intrinsically accounts motion line.7 Immersed embedded taking increasingly position FSI, virtue their geometric flexibility. addition features three subject. difficulty immersed-FSI concerns fact topology geometry background mesh evolve essentially arbitrary manner during dynamics, compromising accuracy formulation. Ho Farhat method equations and, correspondingly, system outputs depend smoothly discrete events associated changes mesh-interface eliminated.8 Fernández Gerosa introduce stable scheme based projective semi-implicit splitting paradigm combination Nitsche-type formulation.9 Huang subsystems co-dimension two, cables, booms risers.10 recent use simulations multi-disciplinary control, design, optimization inversion problems. control pose severe conditions consistency well efficiency procedure. Wick Wollner monolithic gradient-based unsteady adjoint-equation formalism.11 Boncoraglio consider model-reduction multi-parameter linearized constraints.12