340 research outputs found
A stable FSI algorithm for light rigid bodies in compressible flow
In this article we describe a stable partitioned algorithm that overcomes the
added mass instability arising in fluid-structure interactions of light rigid
bodies and inviscid compressible flow. The new algorithm is stable even for
bodies with zero mass and zero moments of inertia. The approach is based on a
local characteristic projection of the force on the rigid body and is a natural
extension of the recently developed algorithm for coupling compressible flow
and deformable bodies. Normal mode analysis is used to prove the stability of
the approximation for a one-dimensional model problem and numerical
computations confirm these results. In multiple space dimensions the approach
naturally reveals the form of the added mass tensors in the equations governing
the motion of the rigid body. These tensors, which depend on certain surface
integrals of the fluid impedance, couple the translational and angular
velocities of the body. Numerical results in two space dimensions, based on the
use of moving overlapping grids and adaptive mesh refinement, demonstrate the
behavior and efficacy of the new scheme. These results include the simulation
of the difficult problem of a shock impacting an ellipse of zero mass.Comment: 32 pages, 20 figure
Strong fluid–solid interactions with segregated CFD solvers
Purpose: A fluid-structure coupling partitioned scheme involving rigid bodies supported by spring-damper systems
is presented. This scheme can be used with already existing fluid flow solvers without the need to modify them.
Design/methodology/approach: The scheme is based on a modified Broyden method. It solves the equations of solid
body motion in which the external forces coming from the flow are provided by a segregated flow solver used as a
black box. The whole scheme is implicit.
Findings: The proposed partitioned method is stable even in the ultimate case of very strong fluid-solid interactions
involving a massless cylinder oscillating with no structural damping. The overhead associated with the coupling
scheme represents an execution time increase by a factor of about 2 to 5, depending on the context. The scheme also
has the advantage of being able to incorporate turbulence modeling directly through the flow solver. It has been tested
successfully with URANS simulations without wall law, thus involving thin high aspect-ratio cells near the wall.
Originality/value: Such problems are known to be very difficult to solve and previous studies usually rely on monolithic approaches. To the authors’ knowledge, this is the first time a partitioned scheme is used to solve fluid-solid
interactions involving massless component
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