About the createPatchDict
 

Dear all,
Could you explain the "neighbourPatch" in createPatchDict and how to select?

The reatePatchDict :
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.0.1 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object createPatchDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// This application/dictionary controls:
// - optional: create new patches from boundary faces (either given as
// a set of patches or as a faceSet)
// - always: order faces on coupled patches such that they are opposite. This
// is done for all coupled faces, not just for any patches created.
// - optional: synchronise points on coupled patches.
// 1. Create cyclic:
// - specify where the faces should come from
// - specify the type of cyclic. If a rotational specify the rotationAxis
// and centre to make matching easier
// - always create both halves in one invocation with correct 'neighbourPatch'
// setting.
// - optionally pointSync true to guarantee points to line up.
// 2. Correct incorrect cyclic:
// This will usually fail upon loading:
// "face 0 area does not match neighbour 2 by 0.0100005%"
// " -- possible face ordering problem."
// - in polyMesh/boundary file:
// - loosen matchTolerance of all cyclics to get case to load
// - or change patch type from 'cyclic' to 'patch'
// and regenerate cyclic as above
// Do a synchronisation of coupled points after creation of any patches.
// Note: this does not work with points that are on multiple coupled patches
// with transformations (i.e. cyclics).
pointSync false;
// Patches to create.
patches
(
{
// Name of new patch
name cyc_half0;
// Dictionary to construct new patch from
patchInfo
{
type cyclic;
neighbourPatch cyc_half1;
// Optional: explicitly set transformation tensor.
// Used when matching and synchronising points.
transform rotational;
rotationAxis (1 0 0);
rotationCentre (0 0 0);
// transform translational;
// separationVector (1 0 0);
// Optional non-default tolerance to be able to define cyclics
// on bad meshes
//matchTolerance 1E-2;
}
// How to construct: either from 'patches' or 'set'
constructFrom patches;
// If constructFrom = patches : names of patches. Wildcards allowed.
patches (periodic1);
// If constructFrom = set : name of faceSet
set f0;
}
{
// Name of new patch
name cyc_half1;
// Dictionary to construct new patch from
patchInfo
{
type cyclic;
neighbourPatch cyc_half0;
// Optional: explicitly set transformation tensor.
// Used when matching and synchronising points.
transform rotational;
rotationAxis ( 0 0 1 );
rotationCentre ( 0.3 0 0 );
}
// How to construct: either from 'patches' or 'set'
constructFrom patches;
// If constructFrom = patches : names of patches. Wildcards allowed.
patches (periodic2);
// If constructFrom = set : name of faceSet
set f0;
}
);
// ************************************************** *********************** //

neighbourPatch
 

neighbourPatch is required in the OF2.0 where, the boundary regions are split into 2 separate patches that are linked to one another in the respective mesh files. You can use splitMesh to split the mesh, where you want your fan BC, and then use createPatch to create the cyclic patches for the fan.