Abstract
In this study the isogeometric B-Rep mortar-based mapping method for geometry models stemming directly from Computer-Aided Design (CAD) is systematically augmented and applied to partitioned Fluid-Structure Interaction (FSI) simulations. Thus, the newly proposed methodology is applied to geometries described by their Boundary Representation (B-Rep) in terms of trimmed multipatch Non-Uniform Rational B-Spline (NURBS) discretizations as standard in modern CAD. The proposed isogeometric B-Rep mortar-based mapping method is herein extended for the transformation of fields between a B-Rep model and a low order discrete surface representation of the geometry which typically results when the Finite Volume Method (FVM) or the Finite Element Method (FEM) are employed. This enables the transformation of such fields as tractions and displacements along the FSI interface when Isogeometric B-Rep Analysis (IBRA) is used for the structural discretization and the FVM is used for the fluid discretization. The latter allows for diverse discretization schemes between the structural and the fluid Boundary Value Problem (BVP), taking into consideration the special properties of each BVP separately while the constraints along the FSI interface are satisfied in an iterative manner within partitioned FSI. The proposed methodology can be exploited in FSI problems with an IBRA structural discretization or to FSI problems with a standard FEM structural discretization in the frame of the Exact Coupling Layer (ECL) where the interface fields are smoothed using the underlying B-Rep parametrization, thus taking advantage of the smoothness that the NURBS basis functions offer. All new developments are systematically investigated and demonstrated by FSI problems with lightweight structures whereby the underlying geometric parametrizations are directly taken from real-world CAD models, thus extending IBRA into coupled problems of the FSI type.
Highlights
Computer-based simulations are playing an ever increasing role in the engineering design and production process as they offer reliable predictions based on computational mod-0123456789().,: volVApostolatos et al Adv
These computational models have been traditionally obtained using the standard Finite Element Method (FEM) [1,2] which is typically applied to Computational Structural Dynamics (CSD) or the Finite Volume Method (FVM) [3,4] which is typically used in Computational Fluid Dynamics (CFD)
The application of the aforementioned method considered is that of the partitioned Fluid-Structure Interaction (FSI) simulations, either directly involving isogeometric structural discretizations or using the geometric parametrization of an Exact Coupling Layer (ECL) for smoothing the description of the interface fields
Summary
It was employed in the context of FSI problems in [33] with standard finite element discretizations and in [34] with isogeometric structural discretizations In this contribution, a mortar-based mapping method on trimmed multipatch NURBS geometries stemming directly from real-world CAD geometries is developed and systematically evaluated which is targeted to partitioned FSI, see in [34]. Since open knot vectors α are considered see “Non-uniform rational b-spline curves” section, surface interpolates the four corners of the control point net The latter property along with the affine covariance of the NURBS basis functions, allows for the application of strong Dirichlet boundary conditions at boundaries of untrimmed patches within NURBS-based IGA. Which are linked to the curvature along the parametric directions θα
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