Changes between Version 5 and Version 6 of GlobalDataExplained

Timestamp:

06/03/11 15:58:19 (14 years ago)

Author:

Brandon Shroyer

Comment:

—

GlobalDataExplained

@@ -40 +40 @@
   * {{{3}}} -- [ReflectingBoundaryCondition Reflecting] boundaries.
 
+ * '''{{{initial_maxspeed}}}''':  The maximum initial wave speed; essentially, the maximum rate at which information can propagate across the grid.  The higher the maximum initial wave speed, the smaller the initial timestep will be.  Timesteps are adaptive in AstroBEAR, so in general it is a good idea to give yourself a higher maximum initial speed than you think you'll need--if the initial speed is too high, the system will adjust.  An {{{initial_maxspeed}}} of about {{{30.d0}}} is common.
+
+ * '''{{{iThreaded}}}''':  Turns threaded execution on or off.  Threading is not fully implemented in AstroBEAR 2.0, so this flag should be left at {{{0}}}.
+
 [[BR]]
 == !LevelData ==
+
+The {{{LevelData}}} namelist contains values that are local to a given level.  Every grid on a given level {{{n}}} will have the same {{{LevelData}}} attributes, but the values for level {{{j != n}}} might be substantially different.
+
+All {{{LevelData}}} variables are multi-element.  The data file should have values for every level from {{{0}}} to {{{MaxLevel}}} (see the [GlobalDataExplained#GlobalData GlobalData] namelist above).
+
+ * '''{{{CoarsenRatio}}}''': The refinement ratio for grids on that level.  A {{{CoarsenRatio}}} of 2 on level ''n'' means that an {{{i*j*k}}} cell refined region on level ''n'' will produce a {{{2i*2j*2k}}} grid on level ''n+1''.  Virtually all of our simulations use {{{CoarsenRatio}}}s of 2.  The {{{CoarsenRatio}}} values should ''always'' be integers.
+
+ * '''{{{qTolerance}}}''':  These tolerances are used within {{{SetErrFlags()}}} to determine whether or not to flag a cell for refinement.  The higher the tolerance, the more extreme the variable gradients have to be to warrant refinement.  The {{{qTolerance}}} variables are double-precision and must be greater than 0.d0, but a wide range of values is possible.  1.d-3 and 1.d-5 are common choices.
+
+ * '''{{{DesiredFillRatios}}}''':  Single or double precision values between 0 and 1.  The desired fill ratio determines what fraction of the cells in a new subgrid must be flagged for refinement.  If a potential subgrid's fill ratio is below its parent grid's {{{DesiredFillRatios}}} value, then AstroBEAR will attempt to break it into smaller grids with higher fill ratios.  Problems with low fill ratios will refine more cells than they need to, but will likely use fewer grids to do so.  It becomes a trade-off between the cost of additional refinement and the cost of grid management and communication.  Typical fill ratios range between .5 to .99 (although .99 can be extremely slow).
 
 == IOData ==