[Einstein Toolkit] #940: McLachlan dissipation error - Trac

1 Jun 2012


      #940: McLachlan dissipation error
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 Reporter:  eschnett               |       Owner:     
     Type:  defect                 |      Status:  new
 Priority:  major                  |   Milestone:     
Component:  EinsteinToolkit thorn  |     Version:     
 Keywords:                         |  
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 A kind person tells me:
I wanted to mention what appears to be a mistake in your dissipation
 calculation.  If you refer to Kreiss-Oliger, or equivalently to
 Dissipation/src/apply_dissipation.F77, you find that there is a sign flip
 at certain orders.  For example, 3rd order dissipation to be used with 2nd
 order differencing, and 7th order dissipation to be used with 6th order
 differencing, both need a negative coefficient.  But you don't appear to
 have such a minus sign (unless I missed it), and your parameter epsdiss is
 constrained to be positive.  It looks to me like PDdissipationNth needs to
 be multiplied by something like (-1)^(fdOrder/2).
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Ticket URL: https://trac.einsteintoolkit.org/ticket/940
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