Changes between Version 25 and Version 26 of ControllingRefinement


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Timestamp:
09/16/11 10:00:56 (13 years ago)
Author:
ehansen
Comment:

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  • ControllingRefinement

    v25 v26  
    120120The most direct and quickest way to change refinement is to change the {{{qTolerance}}} and !DesiredFillRatios arrays which are both located in the {{{global.data}}} file.  Each element of these arrays is specific to that level. For example, the first element is for the root level, the next element is for the 1st level of refinement, and so on. {{{qTolerance}}} effectively sets how large a gradient must be in order for those two cells to be refined.  Higher {{{qTolerance}}} --> less refinement.  !DesiredFillRatios affects the way astrobear lays down grids or patches for refinement.  For example, if the !DesiredFillRatio is 0.7, then the AMR will lay down patches so that at least 70% of each patch contains cells marked for refinement.  As a result of this process, you will often get cells being refined which were not initially marked for refinement.  In general, lower !DesiredFillRatios --> more refinement.  Note that changing these arrays is very problem specific.
    121121
    122 Below are snapshots of the mesh for a simulation of the [wiki:u/ehansen/RT Rayleigh-Taylor Instability].  You are looking at the peak of the interface at t = 4.0 with 2 levels of AMR.  In the first snapshot there is improper nesting.  More refinement at the root level and/or less at the 1st level would fix this. 
     122Below are snapshots of the mesh for a simulation of the [wiki:u/ehansen/RT Rayleigh-Taylor Instability].  You are looking at the peak of the interface at t = 4.0 with 2 levels of AMR.  In the first snapshot there is improper nesting.  More refinement at the root level and/or less at the 1st level would fix this.  Note that in this problem the density gradient is very abrupt, and thus it is possible that while some frames have proper nesting, others may not.
    123123
    124124||  qTolerance = (0.2, 0.2)  !DesiredFillRatios = (0.7, 0.7)  ||  qTolerance = (0.005, 0.3)  !DesiredFillRatios = (0.7, 0.7)  ||