"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:95e7df53-71d1-49ee-b65c-e52ba8c70a55","http://resolver.tudelft.nl/uuid:95e7df53-71d1-49ee-b65c-e52ba8c70a55","New Method for Mesh Moving Based on Radial Basis Function Interpolation","De Boer, A.; Van der Schoot, M.S.; Bijl, H.","","2006","A new point-by-point mesh movement algorithm is developed for the deformation of unstructured grids. The method is based on using radial basis function, RBFs, to interpolate the displacements of the boundary nodes to the whole flow mesh. A small system of equations has to be solved, only involving the nodes on the boundary of the flow domain. Because no grid-connectivity information is needed, this method is very easy to implement, even for 3D applications. There are various RBFs available in literature that can be used for the new method. Therefore, the new algorithm is tested with several RBFs for a variety of problems to investigate which RBF produces the best meshes and which one is the most efficient. The method can handle large mesh deformations caused by translations, rotations and deformations of the boundary of the domain. However, the performance depends on the used RBF. The best accuracy and robustness are obtained with the thin plate spline. When efficiency is more important, a polynomial RBF with compact support is the best choice.","mesh deformation; unstructured meshes; radial basis function interpolation; fluid-structure interaction","en","conference paper","","","","","","","","","","","","","",""
"uuid:2b9f4315-bc5a-4767-a48f-15d5bfb6be96","http://resolver.tudelft.nl/uuid:2b9f4315-bc5a-4767-a48f-15d5bfb6be96","Efficient uncertainty quantification using a two-step approach with chaos collocation","Loeven, A.; Witteveen, J.A.S.; Bijl, H.","","2006","In this paper a Two Step approach with Chaos Collocation for efficient uncertainty quantification in computational fluid-structure interactions is followed. In Step I, a Sensitivity Analysis is used to efficiently narrow the problem down from multiple uncertain parameters to one parameter which has the largest influence on the solution. In Step II, for this most important parameter the Chaos Collocation method is employed to obtain the stochastic response of the solution. The Chaos Collocation method is presented in this paper, since a previous study showed that no efficient method was available for arbitrary probability distributions. The Chaos Collocation method is compared on efficiency with Monte Carlo simulation, the Polynomial Chaos method, and the Stochastic Collocation method. The Chaos Collocation method is non-intrusive and shows exponential convergence with respect to the polynomial order for arbitrary parameter distributions. Finally, the efficiency of the Two Step approach with Chaos Collocation is demonstrated for the linear piston problem with an unsteady boundary condition. A speed-up of a factor of 100 is obtained compared to a full uncertainty analysis for all parameters.","Computational Fluid Dynamics; fluid-structure interaction; non-intrusive; polynomial chaos; stochastic collocation; uncertainty quantification","en","conference paper","","","","","","","","","","","","","",""
"uuid:acaa4adb-e871-4f52-b9a5-cbff381415ae","http://resolver.tudelft.nl/uuid:acaa4adb-e871-4f52-b9a5-cbff381415ae","Comparison of the conservative and a consistent approach for the coupling of non-matching meshes","De Boer, A.; Van Zuijlen, A.H.; Bijl, H.","","2006","In fluid-structure interaction simulations the meshes at the fluid-structure interface usually do not match, because of the different mesh requirements for the flow and structure. The exchange of data over the discrete interface becomes then far from trivial. In this paper we investigate the difference in accuracy and efficiency between a conservative and a consistent coupling approach. This is done for an analytical test problem as well as a quasi-1D FSI problem, for different coupling methods found in literature. It is found that when the coupling method is based on a weak formulation of the coupling conditions the conservative approach is the best choice. For other coupling methods the consistent approach provides the best accuracy and efficiency, because the conservative approach results in unphysical oscillations in the pressure received by the structure and is therefore not consistent.","fluid-structure interaction; partitioned coupling; non-matching meshes; coupling schemes","en","conference paper","","","","","","","","","","","","","",""
"uuid:cb466783-d350-4b74-821b-40c4c6add71c","http://resolver.tudelft.nl/uuid:cb466783-d350-4b74-821b-40c4c6add71c","Two level algorithms for partitioned fluid-structure interaction computations","Bijl, H.; Van Zuijlen, A.H.; Bosscher, S.","","2006","In this paper we use the multigrid algorithm - commonly used to improve the efficiency of the flow solver - to improve the efficiency of partitioned fluid-structure interaction iterations. Coupling not only the structure with the fine flow mesh, but also with the coarse flow mesh (often present due to the multigrid scheme) leads to a significant efficiency improvement. As solution of the flow equations typically takes much longer than the structure solve, and as multigrid is not standard in structure solvers, we do not coarsen the structure or the interface. As a result, the two level method can be easily implemented into existing solvers. Two types of two level algorithms were implemented: 1) Coarse grid correction of the partitioning error and 2) Coarse grid prediction or full multigrid to generate a better initial guess. The resulting schemes are combined with a fourth-order Runge-Kutta implicit time integration scheme. For the linear, one-dimensional piston problem with compressible flow the superior stability, accuracy and efficiency of the two level algorithms is shown. The parameters of the piston problem were chosen such that both a weak and a strong interaction case were obtained. Even the strong interaction case, with a flexible structure, could be solved with our new two level partitioned scheme with just one iteration on the fine grid. This is a major accomplishment as most weakly coupled methods fail in this case. Of the two algorithms the coarse grid prediction or full multigrid method was found to perform best. The resulting efficiency gain for our one-dimensional problem is around a factor of ten for the coarse to intermediate time steps at which the high order time integration methods should be run. For two- and three-dimensional problems the efficiency gain is expected to be even larger.","fluid-structure interaction; domain decomposition; partitioned coupling; multilevel techniques","en","conference paper","","","","","","","","","","","","","",""