| 1. |
- Andreasson, Håkan, 1966
(författare)
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Black hole formation from a complete past for the einstein–vlasov system
- 2014
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Ingår i: International conference on Relativity and Gravitation, 2012, Prague, Czech Republic, 25-29 June 2012. - Cham : Springer International Publishing. - 0930-8989 .- 1867-4941. - 9783319067605 ; 157, s. 11-18
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Konferensbidrag (refereegranskat)abstract
- Anatural question in general relativity is to find initial data for the Einstein equations whose past evolution is regular and whose future evolution contains a black hole. In [1] initial data of this kind is constructed for the spherically symmetric Einstein–Vlasov system. One consequence of the result is that there exists a class of initial data for which the ratio of the Hawking mass (Formula presented) (r) and the area radius r is arbitrarily small everywhere, such that a black hole forms in the evolution. This result is analogous to the result [2] for a scalar field. Another consequence is that there exist black hole initial data such that the solutions exist for all Schwarzschild time t ∈ (−∞,∞). In the present article we review the results in [1].
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| 2. |
- Cederwall, Martin, 1961
(författare)
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Pure spinor superfields - an overview
- 2014
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Ingår i: Springer Proceedings in Physics. - Cham : Springer International Publishing. - 0930-8989 .- 1867-4941. ; 153, s. 61-93
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Konferensbidrag (refereegranskat)abstract
- Maximally supersymmetric theories do not allow off-shell superspace formulations with traditional superfields containing a finite set of auxiliary fields. It has become clear that off-shell supersymmetric action formulations of such models can be achieved by the introduction of pure spinors. In this talk, an overview of this formalism is given, with emphasis on D=10 super-Yang-Mills theory and D=11 supergravity. This a somewhat expanded version of a talk presented at the workshop "Breaking of supersymmetry and ultraviolet divergences in extended supergravity" (BUDS), Laboratori Nazionali di Frascati, March 25-28, 2013.
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| 3. |
- Karlsson, Anna, 1987
(författare)
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Loop amplitude diagrams in manifest, maximal supergravity
- 2014
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Ingår i: Springer Proceedings in Physics. - Cham : Springer International Publishing. - 0930-8989 .- 1867-4941. ; 153
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Konferensbidrag (refereegranskat)abstract
- The issue of finiteness of maximal supergravity has been subject to research for quite some time. Here, we approach that question through an examination of how to describe amplitude diagrams in D=11 maximal supergravity from a field theory point of view. The strength of the formulation is the presence of manifest supersymmetry through the use of pure spinors. An initial analysis of what the subsequent characteristics turn out to be, partly in lower dimensions through dimensional reduction, gives at hand results that agree with previous work, pointing towards a first divergence for the 7-loop contribution to the 4-point amplitude in four dimensions. The text is mainly based on [arXiv:1212.5175] and may be regarded as an introduction to the main points presented there.
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| 4. |
- Kleinhans, David, 1979, et al.
(författare)
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Synthetic turbulence models for wind turbine applications
- 2010
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Ingår i: Springer Proceedings in Physics. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0930-8989 .- 1867-4941. ; 131, s. 111-114
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Konferensbidrag (refereegranskat)abstract
- Wind energy converters such as wind turbines permanently work in the atmospheric boundary layer. For the modelling of the dynamics and for the optimisation of design and material of wind turbines synthetic models for atmospheric turbulence are applied already for a long time. The main purpose of these models is to provide fast and efficient methods for numerical simulation of random fields, that show some characteristic features of atmospheric turbulence. Typically they only have a partial connection to the fundamental equations of fluid dynamics. After a short overview summarizing widespread models by Veers and Mann, that are based on the simulation of random fields in the Fourier domain, advanced models for the simulation of velocity fields are discussed.
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| 5. |
- yilmas, I, 1980, et al.
(författare)
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Application and Comparison of Two Different DNS Algorithms for Simulating Transition to Turbulence in Taylor-Green Vortex Flow
- 2012
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Ingår i: Springer Proceedings in Physics. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0930-8989 .- 1867-4941. ; 141, s. 91-94
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Konferensbidrag (refereegranskat)abstract
- An all-Mach number, fully implicit, non-dissipative DNS algorithm and an incompressible, dissipative DNS algorithm were applied for simulating transition to turbulence in TGV flow to assess their behavior for this flow regime. The all-Mach number solver was developed and parallelized. A method was also adopted to remove oscillating pressure corrections in time. In order to compare the behavior of the algorithms, various flow diagnostics were calculated. The results were also compared to results given in the literature. The development of the flow and the peak structures show some differences due to different dissipative and energy conserving properties of the algorithms. However the physics of TGV flow are well captured by both, even though the grid is not fully resolved.
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| 6. |
- Krajnovic, Sinisa, 1970, et al.
(författare)
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Numerical Simulation of the Flow around a Tall Finite Cylinder Using LES and PANS
- 2010
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Ingår i: Progress in Turbulence III, Springer Proceedings in Physics. Proceedings of the iTi Conference in Turbulence 2008. Bertinoro, ITALY, OCT 12-15.. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0930-8989. - 9783642022241 ; 131, s. 115-118
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Konferensbidrag (refereegranskat)abstract
- Two unsteady numerical techniques, LES and PANS, with difference computer requirements, were used for prediction of the flow around a tall finite cylinder. The well resolved LES was found to predict the flow in agreement with previous experimental observations, while PANS was found to suffer from the combination of k - epsilon model in conjuction with wall function close to the wall of the cylinder and too coarse resolution.
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