HELP! * GREY=local LOCAL HTML version of Foils prepared 15 March 1996

Foil 21 The Lapse and Shift in Gauge Transformations

From Master Foilset of Numerical Formulation and Solution of Collision 0f two Black Holes CPSP713 Case studies in Computational Science -- Spring Semester 1996. by Geoffrey C. Fox * Critical Information in IMAGE
The Lapse describes how much time elapses between two spacial surfaces
The Shift functions N i describe the tangential shift as you move from the t 0 to t 0+ dt spacial surface
Choose Lapse and Shift to:
  • Avoid Unphysical Singularities (One cannot avoid physical black hole singularity
    • Choice of spherical polar coordinates has singularity at radius r=0.
  • Keep Numerical Algorithm Stable
  • Insure Consistency of Constraints

Northeast Parallel Architectures Center, Syracuse University, npac@npac.syr.edu

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