Active flutter suppression, which is a part of the group of flight vehicle technologies known as active controls, is an important contributor to the effective solution of aeroelastic instability pr...

https://arc.aiaa.org/doi/pdf/10.2514/1.C034442

Aircraft Active Flutter Suppression: State of the Art and Technology Maturation Needs

To address the computational challenges associated with contact between moving interfaces, such as those in cardiovascular fluid–structure interaction (FSI), parachute FSI, and flapping-wing aerodynamics, we introduce a space–time (ST) interface-tracking method that can deal with topology change (TC). In cardiovascular FSI, our primary target is heart valves. The method is a new version of the deforming-spatial-domain/stabilized space–time (DSD/SST) method, and we call it ST-TC. It includes a master–slave system that maintains the connectivity of the “parent” mesh when there is contact between the moving interfaces. It is an efficient, practical alternative to using unstructured ST meshes, but without giving up on the accurate representation of the interface or consistent representation of the interface motion. We explain the method with conceptual examples and present 2D test computations with models representative of the classes of problems we are targeting.

Space–time interface-tracking with topology change (ST-TC)

Fluid–structure interaction in partially filled liquid containers: A comparative review of numerical approaches

Flow problems with moving boundaries and interfaces include fluid–structure interaction (FSI) and a number of other classes of problems, have an important place in engineering analysis and design, and offer some formidable computational challenges. Bringing solution and analysis to them motivated the Deforming-Spatial-Domain/Stabilized Space–Time (DSD/SST) method and also the variational multiscale version of the Arbitrary Lagrangian–Eulerian method (ALE-VMS). Since their inception, these two methods and their improved versions have been applied to a diverse set of challenging problems with a common core computational technology need. The classes of problems solved include free-surface and two-fluid flows, fluid–object and fluid–particle interaction, FSI, and flows with solid surfaces in fast, linear or rotational relative motion. Some of the most challenging FSI problems, including parachute FSI, wind-turbine FSI and arterial FSI, are being solved and analyzed with the DSD/SST and ALE-VMS methods as core technologies. Better accuracy and improved turbulence modeling were brought with the recently-introduced VMS version of the DSD/SST method, which is called DSD/SST-VMST (also ST-VMS). In specific classes of problems, such as parachute FSI, arterial FSI, ship hydrodynamics, fluid–object interaction, aerodynamics of flapping wings, and wind-turbine aerodynamics and FSI, the scope and accuracy of the FSI modeling were increased with the special ALE-VMS and ST FSI techniques targeting each of those classes of problems. This article provides an overview of the core ALE-VMS and ST FSI techniques, their recent versions, and the special ALE-VMS and ST FSI techniques. It also provides examples of challenging problems solved and analyzed in parachute FSI, arterial FSI, ship hydrodynamics, aerodynamics of flapping wings, wind-turbine aerodynamics, and bridge-deck aerodynamics and vortex-induced vibrations.

Engineering Analysis and Design with ALE-VMS and Space–Time Methods

Fluid mechanics computation of heart valves with an interface-tracking (moving-mesh) method was one of the classes of computations targeted in introducing the space---time (ST) interface tracking method with topology change (ST-TC). The ST-TC method is a new version of the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) method. It can deal with an actual contact between solid surfaces in flow problems with moving interfaces, while still possessing the desirable features of interface-tracking methods, such as better resolution of the boundary layers. The DSD/SST method with effective mesh update can already handle moving-interface problems when the solid surfaces are in near contact or create near TC, if the "nearness" is sufficiently "near" for the purpose of solving the problem. That, however, is not the case in fluid mechanics of heart valves, as the solid surfaces need to be brought into an actual contact when the flow has to be completely blocked. Here we extend the ST-TC method to 3D fluid mechanics computation of heart valve models. We present computations for two models: an aortic valve with coronary arteries and a mechanical aortic valve. These computations demonstrate that the ST-TC method can bring interface-tracking accuracy to fluid mechanics of heart valves, and can do that with computational practicality.

Space---time fluid mechanics computation of heart valve models

The sloshing effects of an internal fluid on the flutter envelope of an aeroelastic system have received little attention in the open literature. This issue is nevertheless relevant for many aircraft, especially high-performance fighter jets carrying stores. This paper addresses some aspects of this problem as well as related modeling and analysis issues. These include the importance or insignificance of accounting for the hydroelastic effect when modeling an internal fluid and its container as well as accounting for that container when modeling the aerodynamics of the overall aeroelastic system. The paper also reports on the findings of four independent sets of flutter analyses performed for a wing–store test configuration and various fuel fill levels in the subsonic, transonic, and early supersonic regimes. Two of these sets of numerica l experiments relied on a computational-fluid-dynamics-based computational technology, and two of them on the doublet-lattice method or a supersonic lifting-surface theo...

Modeling of Fuel Sloshing and its Physical Effects on Flutter

Various modelling levels to represent internal liquid behaviour in the vibration analysis of complex structures

Incompressible hydroelastic vibrations: finite element modelling of the elastogravity operator

Linearized formulation for fluid-structure interaction: Application to the linear dynamic response of a pressurized elastic structure containing a fluid with a free surface

In the context of the study of structures coupled with internal liquids, we present in this article a theoretical work to treat the coupling between the structure elasticity and the surface tension phenomenon, which has not been the object of specific studies before (according to the authors knowledge). Considering an incompressible and inviscid liquid in an elastic container, an energy approach is used to obtain a variational formulation of the small amplitude vibrations of the coupled problem around the nonlinear static equilibrium position. The incompressibility of the liquid supposed inviscid and the contact condition at the fluid-structure interface are introduced by Lagrange multipliers. Gravitational forces and surface tensions are both taken into account considering their associated potential energies.

Energy approach for static and linearized dynamic studies of elastic structures containing incompressible liquids with capillarity: a theoretical formulation

Jean-Sébastien Schotté

Papers

Modeling of Fuel Sloshing and its Physical Effects on Flutter

Various modelling levels to represent internal liquid behaviour in the vibration analysis of complex structures

Incompressible hydroelastic vibrations: finite element modelling of the elastogravity operator

Linearized formulation for fluid-structure interaction: Application to the linear dynamic response of a pressurized elastic structure containing a fluid with a free surface

Energy approach for static and linearized dynamic studies of elastic structures containing incompressible liquids with capillarity: a theoretical formulation