Coupling fluid (CFD) and structural (FE) models using finite interpolation elements

https://doi.org/10.1016/S1270-9638(00)00111-5Get rights and content

Abstract

In the field of aeroelasticity, interactions between elastic structures and fluid flow are investigated. Recently, numerical aeroelastic models have been built composing those of the combining fluid dynamics (CFD) and the computational structural dynamics (CSD) domains. Since the fluid and the structural models differ in their formulation and discretization, an interface model has to be introduced that represents the connectivity and physical interaction between the two single domain models. In the following, a scheme for coupling fluid (CFD) and structural models (FE) in space is presented which is based on finite interpolation elements. It is applied to static aeroelastic problems, in order to predict the equilibrium of elastic wing models in transonic fluid flow. The structure is represented by finite elements and the related equations are solved using commercial FE analysis codes. The transonic fluid flow is described by the three-dimensional Euler equations, solved by an upwind scheme procedure. The resulting coupled field problem containing the fluid and the structural state equations, is solved by applying a partitioned solution procedure. In each solution step the interface and boundary conditions are exchanged and updated. Here, a fixed-point iteration scheme is used for the coupled aeroelastic equations.

Zusammenfassung

Es wird eine konservative Methode zur Kopplung von räumlich dreidimensionalen, numerischen aerodynamischen (CFD) und elastomechanischen (FE) Modellen vorgestellt, die auf die Anwendung finiter Interpolationselemente beruht. Der Kopplungsalgorithmus erfüllt die Forderung nach Unabängigkeit von den Gleichungen, die das aerodynamische und elastomechanische Modell beschreiben, deren Diskretisierungen und den entsprechenden Lösungsmethoden. Diese Eigenschaft erlaubt einen Austausch der aerodynamischen und elastomechanischen Modelle und Berechnungsverfahren.

Integriert in ein Verfahren zur Vorhersage des statischen aeroelastischen Deformationsverhaltens von Tragflügeln wurden numerische Berechnungen durchgeführt, deren Ergebnisse mit entsprechenden experimentellen Daten verglichen werden. Der Vergleich zeigt eine gute Übereinstimmung der aus den numerischen Berechnungen und dem Experiment gewonnenen Ergebnisse.

Es wird gezeigt, daß die Kopplungsmethode lokal auftretende Unstetigkeitseffekte berücksichtigt und auf komplexere dreidimensionale aeroelastische Modelle, wie sie in der industriellen Praxis auftreten, anwendbar ist.

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    Citation Excerpt :

    Again, there are two fundamental approaches available: mesh-based and mesh-free methods. Mesh-based methods, such as finite-interpolation-elements (FIE), rely on the direct approaches of the individual solvers [16,17]. An example for a mesh-free method is the spline-based moving-least-squares-method (MLS) [18], which interpolates the transfer information between the different interface discretizations.

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