Advances In FSI Using Body-fitted
Unstructured Grids
Author(s)
R. L¨ohner, B. H¨ubner & J. R. Cebral
Abstract
Several algorithms for the loose coupling of fluid and structural dynamics codes
are described. The first class of algorithms treats the displacement of the surface
of structure that is in contact with the fluid. It is shown that a straightforward treatment
of the displacements for arbitrary choice of timesteps can lead to instabilities.
For optimal stability, at each timestep the ending time of the fluid should be just
beyond the ending time of the structure. The second class of algorithms treats the
movement of the flow mesh in an ALE setting. The use of a projective prediction
of mesh velocities, as well as linelet preconditioning for the resulting PCG system,
can significantly reduce the effort required. Examples are included that show the
effectiveness of the proposed procedures.
1 Introduction
While CFD solvers based on adaptive cartesian or unstructured grids are commonly
used for complex Fluid-Structure Interaction (FSI) simulations, for applications
that require the proper resolution of boundary layers the moving, body-fitted
mesh approach with arbitrary Lagrangean–Eulerian (ALE) formulation remains
the only viable option to date. The need to extend the range of applicability of this
type of approach to long-term FSI runs, such as bridges, chimneys and offshore
platforms, has led to a series of algorithmic improvements which are the subject
of this paper. In particular, the following subjects will be treated:
- synchronization of times between loosely coupled CFD and CSD solvers in
order to minimize grid distortion; and
- projective prediction to accelerate the convergence of the PCG solver of the
mesh velocities.
Keywords
Related Book
Other papers in this volume
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