Dynamic Modeling of Mooring Lines Using a FSI Solver Based on OpenFOAM

Transcription

1 Dynamic Modeling of Mooring Lines Using a FSI Solver Based on OpenFOAM 3RD Northern Germany OpenFOAM User Meeting 2015 Author: Co-Authors: H. G. Matthies, C. Borri 3 Northern Germany OpenFOAM User Meeting 2015

2 Aim of the present work A CFD simulation of the whole domain is not affordable! 2/22

3 Methods 3/22

4 Planned Idea and Aims of the present Work Create a numerical model which is suitable for long term simulations. Couple a CFD code with a CSD code in order to understand which are the main physical parameters that govern the problem. Create a tool which is able to predict both the VIV in-line and cross-flow response. Create a reduced order model which could be used instead of Morison s equation. Create a new element that can be added to any CSD code. 4/22

5 The Small Scale FSI Problem Structures and fluids are two different scientific topics and normally they have Different formulations: Lagrangian and Eulerian Different discretization methods: FE and FV Different software Different expertise A monolithical approach is not a natural choiche!! 5/22

6 The Small Scale FSI Problem F OPENFOAM Fluid Computation F Control u u Ff Middleware: CTL Fs us FEAP Solid Computation uf Interpolator Communication of Fluid and Solid Computations Development of a Master Code Development of a suitable Interpolator Reuse existing software The coupling is realized using the software component approach 6/22

7 The Coupling Algorithm A Gauss-Seidel algorithm with an Aitken s relaxation technique has been used for the coupled problem. 7/22

8 The idea of software components The basic idea of software components is to make an executable component from a piece of code which fits the specification of an interface. Different components can communicate each other through their interface and a middleware. Different components can be written with different programming languages. Different components can be located on different computers. You can use existing codes almost as black boxes. 8/22

9 The idea of software components How to build a component One needs to define a list of methods that it should perform and that is available by other components. The list of methods defines the interface of the software component. The COMPONENT TEMPLATE LIBRARY (CTL), developed by Rainer Niekamp, is used as middleware. A component of OPEN FOAM needs to be developed. A component of FEAP needs to be developed. To create a component one needs to have access to the code. It means only open source software can be used!! 9/22

10 The idea of software components CoFOAM F F Cops OPENFOAM Control FEAP u u Ff Middleware: CTL CoFEAP Fs us uf Interpolat Interpolator or CoFOAM is the component of OpenFoam. CoFEAP is the component of Feap. Cops and Interpolator are themselves components. 10/22

11 The idea of software components Few words about The CTL It is a C++ Template Library developed at the Institute of Scientific Computing of TU Braunschweig by Rainer Niekamp. Comparable Software Technology are CORBA or CCA. It can couple together several programming languages: C/C++, Fortran, Java, Matlab and Python. It has been successfully used for several applications. SOME EXAMPLES T. Srisupattarawanit Offshore Wind Turbine C. Kassiotis FSI with OpenFoam 11/22

12 The idea of software components Few words about cofeap Component based on FEAP FEAP is an open source FEM solver developed by Prof. Taylor and his coo-workers a the University of Berkeley. It can handle a wide range of linear and nonlinear structural problems. Written mainly in Fortran90. 12/22

13 The idea of software components Call CoFOAM from the master component Call CoFEAP from the master component 13/22

14 The idea of software components How an interface looks like 14/22

15 The idea of software components How to implement a new method: Example with pimpledymfoam Solver 15/22

16 The cable example: The Fluid Sub-Problem Mesh 2D view Mesh 3D view Pre ssu e r Ou try tlet e m Sym e n pla slip ve ty loc i in le t Fluid Sub-Problem is solved with OpenFOAM. Inlet velocity of 1 m/s. slip ry t e m m Sy ne a pl Fluid solved with LES and one-eq eddy sub grid scale model. The PIMPLE algorithm has been used. 16/22

17 The cable example:the Fluid Sub-Problem Validation of the Fluid Sub-Problem Lift coefficient Comparison with experimental and previous numerical results Drag coefficient 17/22

18 The cable example: The Solid and Mesh-Motion Problem The beam has been modelled with a 3D geometrically exact beam element. A suitable mapping between the beam nodes (monodimensional) and the FSI interface has been developed. A generalized HHT-α time integrazion scheme has been used A laplacian smoothing algorithm has been used for the mesh motion problem 18/22

19 The Cable Example 19/22

20 Conclusions An FSI solver using the software component approach has been developed. Using this approach we have several advantages: You can use popular and validated FEM and FVM solvers for the structure and fluid part. You can use codes written in different programming languages. It is more efficient to use already developed models. Disadvantages of component technology and software re-use Only partitioned approaches are allowed. 20/22

21 Some References, Hermann G. Matthies, Claudio Borri. A Reduced Order Model for the Simulation of Mooring Cable Dynamics. In Proceedings of MARINE2015, ECCOMAS conference. Tarin Srisupattarawanit, Rainer Niekamp, Hermann G. Matthies. A Coupled Multi-Physics Model for Dynamics of Offshore Wind Energy Converter. Development and Applications of Oceanic Engineering, 3:1-10, 2014 Adnan Ibrahimbegovic, Rainer Niekamp, Christophe Kassiotis, Damijan Markovic, and Hermann G. Matthies. Code-coupling strategy for efficient development of computer software in multiscale and multiphysics nonlinear evolution problems in computational mechanics. Advances in Engineering Software, 72:8-17, 2014 Christophe Kassiotis, Adnan Ibrahimbegovic, Rainer Niekamp, and Hermann G. Matthies. Nonlinear-fluid structure interaction problem. Part I: implicit partitioned algorithm, nonlinear stability proof and validation examples. Computational Mechanics, 47: , /22

22 Thank you For the Attention!! 22/22