Changes between Version 2 and Version 3 of AthenaDocsPGCentering


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Timestamp:
May 12, 2010 11:26:37 PM (7 years ago)
Author:
jmstone
Comment:

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  • AthenaDocsPGCentering

    v2 v3  
    33'''[wiki:WikiStart Wiki]/[wiki:AthenaDocs Documentation]/[wiki:AthenaDocsPG ProgrammerGuide]/Centering'''
    44
    5 A final, important characeristic of the Mesh used in Athena is the centering of the conserved variables in Grid cells.
     5A final, important characteristic of the Mesh used in Athena is the centering of the conserved variables in Grid cells.
    66The figure below shows this centering.  The volume-averaged conserved variables '''U''' = (density, momentum, total energy)
    7 are stored are cell-centers.  The components of the area-averaged magnetic field are stored at the corresponding cell faces.
     7are stored at cell-centers.  The components of the area-averaged magnetic field are stored at the corresponding cell faces.
    88Additional copies of the volume-averaged cell-centered magnetic field are stored in '''U''', however these are not
    99the fundamental description of the field (they are computed from the face-centered fields).
     
    1111[[Image(Centering.png,50%)]]
    1212
    13 The cell-centered variables are stored in the [wiki:AthenaDocsPGConsS Conserved Variable structure], which is
     13The cell-centered variables are stored in the [wiki:AthenaDocsPGConsPrim Conserved Variable structure], which is
    1414a 3D array in the [wiki:AthenaDocsPGGridS Grid structure].  Components of this array are addressed using integer
    15 indices with the {{{i}}} (x1) index incremented fastest: {{{{U[k][j][i]}}}.
     15indices with the {{{i}}} (x1) index incremented fastest: {{{U[k][j][i]}}}.
    1616
    17 THe face centered magnetic fields are stored as 3D arrays directly in the [wiki:AthenaDocsPGGridS Grid structure].
     17The face centered magnetic fields are stored as 3D arrays directly in the [wiki:AthenaDocsPGGridS Grid structure].
    1818The array element on the ''left-interface'' is given the index {{{i}}}, that is Bx,,i-1/2,j,k,, = {{{B1i[k][j][i]}}}.