Niemeyer, J

[["dc.bibliographiccitation.artnumber","Code 103036"],["dc.bibliographiccitation.firstpage","79"],["dc.bibliographiccitation.lastpage","91"],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Maier, A."],["dc.contributor.author","Hupp, M."],["dc.contributor.author","Federrath, C."],["dc.contributor.author","Niemeyer, J."],["dc.contributor.editor","Wagner, Siegfried"],["dc.contributor.editor","Steinmetz, Matthias"],["dc.contributor.editor","Bode, Arndt"],["dc.contributor.editor","Brehm, Matthias"],["dc.date.accessioned","2020-07-09T08:29:54Z"],["dc.date.available","2020-07-09T08:29:54Z"],["dc.date.issued","2009"],["dc.description.abstract","For the treatment of astrophysical flows with high Mach numbers and high Reynolds numbers, we proposed a method called FEARLESS (Fluid mEchanics with Adaptively Refined Large-Eddy SimulationS) that combines adaptive methods and subgrid scale modeling. The basic idea is to resolve anisotropic, supersonic flow features (shocks, collapsing regions) using AMR (AdaptiveMesh Refinement), whereas length scales dominated by isotropic, subsonic turbulence are described by a subgrid scale model. Implementing FEARLESS into the open source AMR code Enzo, we successfully tested the new method both in hydrodynamic and selfgravitating turbulence simulations. In the next phase of the project, FEARLESS will be applied to star formation and galactic disk simulations."],["dc.identifier.doi","10.1007/978-3-540-69182-2_7"],["dc.identifier.scopus","2-s2.0-84897691411"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/66904"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-84897691411&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.publisher","Kluwer Academic Publishers"],["dc.relation.conference","2007 3rd Joint HLRB and KONWIHR Result and Reviewing Workshop"],["dc.relation.eventend","2007-12-04"],["dc.relation.eventlocation","Garching/Munich"],["dc.relation.eventstart","2007-12-03"],["dc.relation.isbn","978-354069181-5"],["dc.relation.ispartof","High Performance Computing in Science and Engineering, Garching/Munich 2007 - Transactions of the 3rd Joint HLRB and KONWIHR Status and Result Workshop"],["dc.title","Star Formation in the Turbulent Interstellar Medium and Its Implications on Galaxy Evolution"],["dc.type","conference_paper"],["dc.type.internalPublication","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","127"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","145"],["dc.bibliographiccitation.volume","494"],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Federrath, C."],["dc.contributor.author","Hupp, M."],["dc.contributor.author","Kern, S. A. W."],["dc.contributor.author","Niemeyer, J. C."],["dc.date.accessioned","2020-07-21T06:04:04Z"],["dc.date.available","2020-07-21T06:04:04Z"],["dc.date.issued","2009"],["dc.description.abstract","We performed numerical simulations of supersonic isothermal turbulence driven by mostly compressive large-scale forcing, using both a static grid and adaptive mesh refinement with an effective resolution N=768^3. After a transient phase dominated by shocks, turbulence evolves into a steady state with an RMS Mach number about 2.5, in which cloud-like structures of over-dense gas are surrounded by highly rarefied gas. The index of the turbulence energy spectrum function beta = 2.0 in the shock-dominated phase. As the flow approaches statistical equilibrium, the spectrum flattens, with beta = 1.9. For the scaling exponent of the root mean square velocity fluctuation, we obtain gamma = 0.43 from the velocity structure functions of second order. These results are well within the range of observed scaling properties for the velocity dispersion in molecular clouds. Calculating structure functions of order p=1,...,5, we find for all scaling exponents significant deviations from the Kolmogorov-Burgers model proposed by Boldyrev. Our results are very well described by a general log-Poisson model with a higher degree of intermittency, which implies an influence of the forcing on the scaling properties. Contrary to previous numerical results for isothermal turbulence, we obtain a skewed probability density function of the mass density fluctuations that is not consistent with log-normal statistics and entails a substantially higher fraction of mass in the density peaks than implied by the Padoan-Nordlund relation between the variance of the density fluctuations and the Mach number. In conclusion, it seems necessary to account for the production mechanism of turbulence in the ISM."],["dc.identifier.doi","10.1051/0004-6361:200809967"],["dc.identifier.scopus","2-s2.0-59449103936"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/67312"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-59449103936&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.title","Numerical simulations of compressively driven interstellar turbulence I. Isothermal gas"],["dc.type","journal_article"],["dc.type.internalPublication","no"],["dspace.entity.type","Publication"]]