| 1. |
- Hoffman, Johan, 1974-, et al.
(författare)
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Computability and Adaptivity in CFD
- 2018
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Ingår i: Encyclopedia of Computational Mechanics. - : John Wiley & Sons.
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Bokkapitel (refereegranskat)
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| 2. |
- Hoffman, Johan, 1974-, et al.
(författare)
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Turbulent flow and Fluid–structure interaction
- 2012
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Ingår i: Lecture Notes in Computational Science and Engineering. - : Springer Science and Business Media Deutschland GmbH. ; , s. 543-552
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Bokkapitel (refereegranskat)abstract
- The FEniCS Project aims towards the goals of generality, efficiency, and simplicity, concerning mathematical methodology, implementation and application, and the Unicorn project is an implementation aimed at FSI and high Re turbulent flow guided by these principles. Unicorn is based on the DOLFIN/FFC/FIAT suite and the linear algebra package PETSc. We here present some key elements of Unicorn, and a set of computational results from applications. The details of the Unicorn implementation are described in Chapter 18.
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| 3. |
- Hoffman, Johan, 1974-, et al.
(författare)
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Unicorn : A unified continuum mechanics solver
- 2012
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Ingår i: Lecture Notes in Computational Science and Engineering. - : Springer Science and Business Media Deutschland GmbH. ; , s. 339-361
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Bokkapitel (refereegranskat)abstract
- This chapter provides a description of the technology of Unicorn focusing on simple, efficient and general algorithms and software for the Unified Continuum (UC) concept and the adaptive General Galerkin (G2) discretization as a unified approach to continuum mechanics. We describe how Unicorn fits into the FEniCS framework, how it interfaces to other FEniCS components, what interfaces and functionality Unicorn provides itself and how the implementation is designed. We also present some examples in fluid–structure interaction and adaptivity computed with Unicorn.
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| 4. |
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| 5. |
- Spühler, Jeannette H., et al.
(författare)
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3D Fluid-Structure Interaction Simulation of Aortic Valves Using a Unified Continuum ALE FEM Model
- 2018
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Ingår i: Frontiers in Physiology. - : Frontiers Media S.A.. - 1664-042X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Due to advances in medical imaging, computational fluid dynamics algorithms and high performance computing, computer simulation is developing into an important tool for understanding the relationship between cardiovascular diseases and intraventricular blood flow. The field of cardiac flow simulation is challenging and highly interdisciplinary. We apply a computational framework for automated solutions of partial differential equations using Finite Element Methods where any mathematical description directly can be translated to code. This allows us to develop a cardiac model where specific properties of the heart such as fluid-structure interaction of the aortic valve can be added in a modular way without extensive efforts. In previous work, we simulated the blood flow in the left ventricle of the heart. In this paper, we extend this model by placing prototypes of both a native and a mechanical aortic valve in the outflow region of the left ventricle. Numerical simulation of the blood flow in the vicinity of the valve offers the possibility to improve the treatment of aortic valve diseases as aortic stenosis (narrowing of the valve opening) or regurgitation (leaking) and to optimize the design of prosthetic heart valves in a controlled and specific way. The fluid-structure interaction and contact problem are formulated in a unified continuum model using the conservation laws for mass and momentum and a phase function. The discretization is based on an Arbitrary Lagrangian-Eulerian space-time finite element method with streamline diffusion stabilization, and it is implemented in the open source software Unicorn which shows near optimal scaling up to thousands of cores. Computational results are presented to demonstrate the capability of our framework.
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| 6. |
- Spühler, Jeannette Hiromi, 1981-, et al.
(författare)
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A High Performance Computing Framework for Finite Element Simulation of Blood Flow in the Left Ventricle of the Human Heart
- 2020
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Ingår i: Lecture Notes in Computational Science and Engineering. - Cham : Springer. ; , s. 155-164
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Konferensbidrag (refereegranskat)abstract
- We present a high performance computing framework for finite element simulation of blood flow in the left ventricle of the human heart. The mathematical model is described together with the discretization method and the parallel implementation in Unicorn which is part of the open source software framework FEniCS-HPC. We show results based on patient-specific data that capture essential features observed with other computational models and imaging techniques, and thus indicate that our framework possesses the potential to provide relevant clinical information for diagnosis and medical treatment. Several other studies have been conducted to simulate the three dimensional blood flow in the left ventricle of the human heart with prescribed wall movement. Our contribution to the field of cardiac research lies in establishing an open source framework modular both in modelling and numerical algorithms.
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| 7. |
- Degirmenci, Niyazi Cem, et al.
(författare)
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A Unified Numerical Simulation of Vowel Production That Comprises Phonation and the Emitted Sound
- 2017
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Ingår i: Proceedings of the Annual Conference of the International Speech Communication Association, INTERSPEECH 2017. - : The International Speech Communication Association (ISCA). ; , s. 3492-3496
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Konferensbidrag (refereegranskat)abstract
- A unified approach for the numerical simulation of vowels is presented, which accounts for the self-oscillations of the vocal folds including contact, the generation of acoustic waves and their propagation through the vocal tract, and the sound emission outwards the mouth. A monolithic incompressible fluid-structure interaction model is used to simulate the interaction between the glottal jet and the vocal folds, whereas the contact model is addressed by means of a level set application of the Eikonal equation. The coupling with acoustics is done through an acoustic analogy stemming from a simplification of the acoustic perturbation equations. This coupling is one-way in the sense that there is no feedback from the acoustics to the flow and mechanical fields. All the involved equations are solved together at each time step and in a single computational run, using the finite element method (FEM). As an application, the production of vowel [i] has been addressed. Despite the complexity of all physical phenomena to be simulated simultaneously, which requires resorting to massively parallel computing, the formant locations of vowel [i] have been well recovered.
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| 8. |
- Hinchcliffe Voglio, Gabriela, 1981-
(författare)
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Jaget, laget, Dotterbolaget : En studie av feministiskt nätverkande och rummets betydelse
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This research explores how entrepreneurship interacts with feministic political commitments and praxis. It shows that this interaction is intimately shaped by its spatial setting, in this case Möllevången in the city of Malmö, Sweden. For a long time, the independent comics industry in Sweden has had men in leading positions and the medium has had masculinist connotations. My thesis shows that for women and transgender persons working in such a male-dominated industry, networking and collaborating are crucial for succeeding and staying in business. The particular network studied here is Dotterbolaget, a women and transgender separatist comic’s network based in Malmö.Dotterbolaget practices a feministic approach. The thesis analyses firstly its work practices and secondly the motives animating their adoption. Avoiding competition and promoting collaboration are important factors. So too is finding a means of motivation other than monetary, such as having fun and creating a professional environment for one another. The analysis also considers the spatial setting of the network, showing the deep significance of physical place. Finally, the non-hierarchal form of the network is considered. What does it mean to work as a comic’s artist without hierarchies in an individualised society? What tensions and strengths does such an organisational form give rise to?
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| 9. |
- Jansson, Johan, et al.
(författare)
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Adaptive unified continuum FEM modeling of a 3D FSI benchmark problem
- 2017
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Ingår i: International Journal for Numerical Methods in Biomedical Engineering. - : Wiley-Blackwell. - 2040-7939 .- 2040-7947. ; 33:9
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we address a 3D fluid-structure interaction benchmark problem that represents important characteristics of biomedical modeling. We present a goal-oriented adaptive finite element methodology for incompressible fluid-structure interaction based on a streamline diffusion–type stabilization of the balance equations for mass and momentum for the entire continuum in the domain, which is implemented in the Unicorn/FEniCS software framework. A phase marker function and its corresponding transport equation are introduced to select the constitutive law, where the mesh tracks the discontinuous fluid-structure interface. This results in a unified simulation method for fluids and structures. We present detailed results for the benchmark problem compared with experiments, together with a mesh convergence study.
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| 10. |
- Moragues Ginard, M, et al.
(författare)
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Simulation of floating platforms for marine energy generation
- 2018
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Ingår i: 10th International Conference on Computational Fluid Dynamics, ICCFD 2018. - : International Conference on Computational Fluid Dynamics 2018.
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Konferensbidrag (refereegranskat)abstract
- The goal of this work is to study the dynamics of floating platforms that are designed for marine energy generation. This work is done in collaboration with Tecnalia R&I, a company settled in the Basque Country which designs this kind of platforms. To our purpose we present a method for the simulation of two-phase flow with the presence of floating bodies. We consider the variable density incompressible Navier-Stokes equations and discretize them by the finite element method with a variational multiscale stabilization. A level-set type method is adopted to model the interphase between the two fluids. The mixing or smearing in the interphase is prevented with a compression technique. Turbulence is implicitly modeled by the numerical stabilization. The floating device simulation is done by a rigid body motion scheme where a deforming mesh approach is used. The mesh deforms elastically following the movement of the body. Simulation of a decay test on a cube is performed and the results are presented in this paper. All the simulations are done with the open source finite elements parallel software FEniCS-HPC.
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