Performance of partitioned procedures in fluid–structure interaction

Computer Methods in Applied Mechanics and Engineering

Vierendeels

2011

Self Cite

In partitioned fluid-structure interaction simulations, the flow equations and the structural equations are solved separately. As a result, a coupling algorithm is needed to enforce the equilibrium on the fluid-structure interface in cases with strong interaction. This coupling algorithm performs coupling iterations between the solver of the flow equations and the solver of the structural equations. Current coupling algorithms couple one flow solver with one structural solver. Here, a new class of multi-solver quasi-Newton coupling algorithms for unsteady fluidstructure interaction simulations is presented. More than one flow solver and more than one structural solver are used for a single simulation. The numerical experiments demonstrate that the duration of a simulation decreases as the number of solvers is increased.

Section: Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multi-solver algorithms for the partitioned simulation of fluid–structure interaction

Computer Methods in Applied Mechanics and Engineering

Vierendeels

2011

Self Cite

“…However, this so-called Gauss-Seidel scheme does not converge for this case, which is well understood [4,10,8]. Instead, the Interface Quasi-Newton algorithm with an approximation for the Inverse of the Jacobian from a Least-Squares model (IQN-ILS) has been applied [9,11]. This coupling scheme uses the displacement and stress on the fluid-structure interface during the coupling iterations to accelerate the convergence of these iterations.…”

Section: Three-dimensional Aneurysm Modelmentioning

confidence: 99%

“…The geometry of the model is however simplified and not patient-specific. The fluid-structure interaction is simulated by coupling [9,11] a black-box computational fluid dynamics (CFD) solver with a black-box computational structural dynamics (CSD) solver. Consequently, adjoint techniques are not applicable.…”

Section: (Sbo)mentioning

confidence: 99%

Inverse modelling of an aneurysm’s stiffness using surrogate-based optimization and fluid-structure interaction simulations

Couckuyt

Vierendeels

et al. 2012

Struct Multidisc Optim

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Characterization of the mechanical properties of arterial tissues is highly relevant. In this work, we apply an inverse modelling approach to a model accounting for an aneurysm and the distal part of the circulation which can be modified using two independent stiffness parameters. For given values of these parameters, the position of the arterial wall as a function of time is calculated using a forward simulation which takes the fluid-structure interaction (FSI) into account. Using this forward simulation, the correct values of the stiffness parameters are obtained by minimizing a cost function, which is defined as the difference between the forward simulation and a measurement. The minimization is performed by means of surrogate-based optimization using a Kriging model combined with the expected improvement infill criterion. The results show that the stiffness parameters converge to the correct values, both for a zero-dimensional and for a three-dimensional model of the aneurysm.

“…However, Gauss-Seidel iterations are often unstable if the ratio of the fluid density to the structure density is high, among other reasons [24,25]. In comparisons consisting of several test cases, IQN-ILS requires fewer coupling iterations per time step than Aitken relaxation or Interface GMRES [22], and the computational cost ratio of a partitioned simulation with IQN-ILS to a monolithic simulation ranges from 0.56 to 3.16 [26]. Therefore, IQN-ILS is selected as coupling algorithm.…”

Section: Introductionmentioning

confidence: 99%

Partitioned solution of an unsteady adjoint for strongly coupled fluid-structure interactions and application to parameter identification of a one-dimensional problem

Hojjat

Stavropoulou

et al. 2012

Struct Multidisc Optim

Self Cite

Unsteady fluid-structure interaction (FSI) simulations are generally time-consuming. Gradient-based methods are preferred to minimise the computational cost of parameter identification studies (and more in general optimisation) with a high number of parameters. However, calculating the cost function's gradient using finite differences becomes prohibitively expensive for a high number of parameters. Therefore, the adjoint equations of the unsteady FSI problem are solved to obtain this gradient at a cost almost independent of the number of parameters.Here, both the forward and the adjoint problems are solved in a partitioned way, which means that the flow equations and the structural equations are solved separately. The application of interest is the identification of the arterial wall's stiffness by comparing the motion of the arterial wall with a reference, possibly obtained from non-invasive imaging. Due to the strong interaction between the fluid and the structure, quasi-Newton coupling iterations are applied to stabilise the partitioned solution of both the forward and the adjoint problem.