Performance of a new partitioned procedure versus a monolithic procedure in fluid–structure interaction

Abstract

a b s t r a c tFluid-structure interaction (FSI) can be simulated in a monolithic way by solving the flow and structural equations simultaneously and in a partitioned way with separate solvers for the flow equations and the structural equations. A partitioned quasi-Newton technique which solves the coupled problem through nonlinear equations corresponding to the interface position is presented and its performance is compared with a monolithic Newton algorithm. Various structural configurations with an incompressible fluid are solved, and the ratio of the time for the partitioned simulation, when convergence is reached, to the time for the monolithic simulation is found to be between 1/2 and 4. However, in this comparison of the partitioned and monolithic simulations, the flow and structural equations have been solved with a direct sparse solver in full Newton-Raphson iterations, only relatively small problems have been solved and this ratio would likely change if large industrial problems were considered or if other solution strategies were used.

Stability analysis of Gauss–Seidel iterations in a partitioned simulation of fluid–structure interaction

“…The IQN-ILS algorithm constructs a vector space that grows during the coupling iterations and it behaves like a Newton algorithm for the part of the error in this vector space and like Gauss-Seidel iterations for the other part. More information on this technique can be found in [5]. Fig.…”

“…The convergence of Gauss-Seidel iterations is improved by Aitken relaxation [1] which uses a dynamically-adapted relaxation factor. Faster convergence is obtained with Newton methods [2] or in case of black-box solvers with the Interface Generalized Minimum Residual method [3] or with quasi-Newton methods like the interface block quasi-Newton method with approximate Jacobians from least-squares models (IBQN-LS) [4] and the interface quasi-Newton method with inverse Jacobian from a least-squares model (IQN-ILS) [5]. In case of weak interaction between the fluid and the solid, e.g.…”

Assessment of the Fluid-Structure Interaction Capabilities for Aeronautical Applications of the Open-Source Solver Su2.

“…However, low convergence and even divergence has been reported when density ratios are low, the flow is incompressible or the structural deformations are large [40][41][42]. One common strategy to improve the convergence of the scheme is the use of high-order displacement predictors combined with the employment of relaxation techniques [35,40,43,44].…”

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

“…programmes which calculate an output for a given input, but whose internal algorithms can neither be accessed nor modified. These methods include Gauss-Seidel iterations, Gauss-Seidel iterations with Aitken relaxation [18][19][20], interface GMRES [21] and interface quasi-Newton (IQN-ILS) iterations [22,23]. 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].…”

“…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.…”