Periodic Boundary Conditions

PUGH can implement periodic boundary conditions during the synchronization of grid functions. Although this may at first seem a little confusing, and unlike the usual use of boundary conditions which are directly called from evolution routines, it is the most efficient and natural place for periodic boundary conditions.

PUGH applies periodic conditions by simply communicating the appropriate ghostzones between ``end'' processors. For example, for a 1D domain with two ghostzones, split across two processors, Figure I1.1 shows the implementation of periodic boundary conditions.

Figure: Implementation of periodic boundary conditions for a 1D domain, with two ghostzones, split across two processors. The lines labelled A show the standard communications during synchronisation, the lines labelled B show the additional communications for periodic boundary conditions.

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Periodic boundary conditions are applied to all grid functions, by default they are applied in all directions, although this behaviour can be customised to switch them off in given directions.

By default, no periodic boundary conditions are applied. To apply periodic boundary conditions in all directions, set

  PUGH::periodic = "yes"

To apply periodic boundary conditions in just the x- and y- directions in a 3 dimensional domain, use

  PUGH::periodic = "yes"
  PUGH::periodic_z = "no"