Title:
Scaling of turbulence and turbulent mixing using Terascale numerical simulations

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dc.contributor.advisor Yeung, Pui-Kuen
dc.contributor.author Donzis, Diego Aaron en_US
dc.contributor.committeeMember Menon, Suresh
dc.contributor.committeeMember Neitzel, Paul
dc.contributor.committeeMember Sreenivasan, Katepalli
dc.contributor.committeeMember Webster, Donald R.
dc.contributor.department Aerospace Engineering en_US
dc.date.accessioned 2008-02-07T18:38:14Z
dc.date.available 2008-02-07T18:38:14Z
dc.date.issued 2007-08-09 en_US
dc.description.abstract Fundamental aspects of turbulence and turbulent mixing are investigated using direct numerical simulations (DNS) of stationary isotropic turbulence, with Taylor-scale Reynolds numbers ranging from 8 to 650 and Schmidt numbers from 1/8 to 1024. The primary emphasis is on important scaling issues that arise in the study of intermittency, mixing and turbulence under solid-body rotation. Simulations up to 2048^3 in size have been performed using large resource allocations on Terascale computers at leading supercomputing centers. Substantial efforts in algorithmic development have also been undertaken and resulted in a new code based on a two-dimensional domain decomposition which allows the use of very large number of processors.Benchmark tests indicate very good parallel performance for resolutions up to 4096^3 on up to 32768 processors. Investigation of intermittency through the statistics of dissipation and enstrophy in a series of simulations at the same Reynolds number but different resolution indicate that accurate results in high-order moments require a higher degree of fine-scale resolution than commonly practiced. At the highest Reynolds number in our simulations (400 and 650) dissipation and enstrophy exhibit extreme fluctuations of O(1000) the mean which have not been studied in the literature before and suggest a universal scaling of small scales. Simulations at Reynolds number of 650 on 2048^3 grids with scalars at Sc=1/8 and 1 have allowed us to obtain the clearest evidence of attainment of inertial-convective scaling in the scalar spectrum in numerical simulations to date whereas results at high Sc support k^{-1} viscous-convective scaling. Intermittency for scalars as measured by the tail of the PDF of scalar dissipation and moments of scalar gradient fluctuations is found to saturate at high Sc. Persistent departures from isotropy are observed as the Reynolds number increases. However, results suggest a return to isotropy at high Schmidt numbers, a tendency that appears to be stronger at high Reynolds numbers. The effects of the Coriolis force on turbulence under solid-body rotation are investigated using simulations on enlarged solution domains which reduce the effects of periodic boundary conditions. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/19794
dc.publisher Georgia Institute of Technology en_US
dc.subject Turbulence en_US
dc.subject Fluid dynamics en_US
dc.subject Large scale simulations en_US
dc.subject Direct numerical simulations en_US
dc.subject.lcsh Turbulence
dc.subject.lcsh Algorithms
dc.subject.lcsh Scaling laws (Statistical physics)
dc.subject.lcsh Energy dissipation
dc.subject.lcsh Computer simulation
dc.title Scaling of turbulence and turbulent mixing using Terascale numerical simulations en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Yeung, Pui-Kuen
local.contributor.corporatename College of Engineering
local.contributor.corporatename Daniel Guggenheim School of Aerospace Engineering
local.relation.ispartofseries Doctor of Philosophy with a Major in Aerospace Engineering
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