Abstract/Details

Practical implementation of robust preconditioners for optimized multistage flow solvers


2005 2005

Other formats: Order a copy

Abstract (summary)

Explicit multistage multigrid methods have carved their niche in the solution of complex inviscid and viscous flows. Because of their scalable parallel implementations, they have been a popular choice for the solution of large-scale, complex configuration problems. The convergence rate of these methods deteriorates when they face problems such as numerical stiffness or directional decoupling that result from propagative disparity, cell stretching, and flow alignment. Moreover, in the limit of low Mach numbers, most compressible flow solvers become ill-conditioned in addition to losing accuracy. It is possible to improve existing codes that typically use local time-stepping by using squared preconditioning schemes that combine Block-Jacobi preconditioning with low-Mach preconditioning. A robust and practical implementation of a squared preconditioner is possible for both Euler and Navier-Stokes equations when using an analytical form in entropy variables and their corresponding transformation matrices. Particular attention must be given to entropy fix and limiting techniques. Results of this squared preconditioned approach are presented for both two- and three-dimensional test cases. For these test cases the preconditioning produces convergence acceleration for all Mach numbers while always maintaining the accuracy of the solution. Additional convergence acceleration can be obtained via the optimization of various input parameters such as multistage coefficients, artificial dissipation coefficients and the CFL numbers.

Indexing (details)


Subject
Aerospace materials
Classification
0538: Aerospace materials
Identifier / keyword
Applied sciences; Flow solver; Preconditioners
Title
Practical implementation of robust preconditioners for optimized multistage flow solvers
Author
Hosseini, Kaveh
Number of pages
140
Publication year
2005
Degree date
2005
School code
0212
Source
DAI-B 66/04, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
0542083736, 9780542083730
Advisor
Alonso, Juan
University/institution
Stanford University
University location
United States -- California
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3171644
ProQuest document ID
305436385
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/305436385
Access the complete full text

You can get the full text of this document if it is part of your institution's ProQuest subscription.

Try one of the following:

  • Connect to ProQuest through your library network and search for the document from there.
  • Request the document from your library.
  • Go to the ProQuest login page and enter a ProQuest or My Research username / password.