armi.reactor.grids.hexagonal module

class armi.reactor.grids.hexagonal.HexGrid(unitSteps=(0, 0, 0), bounds=(None, None, None), unitStepLimits=((0, 1), (0, 1), (0, 1)), offset=None, geomType='', symmetry='', armiObject=None)

Bases: StructuredGrid

Has 6 neighbors in plane.

It is recommended to use fromPitch() rather than calling the __init__ constructor directly.

Notes

In an axial plane (i, j) are as follows (second one is pointedEndUp):

        ( 0, 1)
 (-1, 1)       ( 1, 0)
        ( 0, 0)
 (-1, 0)       ( 1,-1)
        ( 0,-1)


    ( 0, 1) ( 1, 0)

(-1, 1) ( 0, 0) ( 1,-1)

    (-1, 0) ( 0,-1)

Implementation: ARMI supports a Hexagonal mesh. IMPL_REACTOR_MESH_2

signature: HexGrid links outgoing: REQ_REACTOR_MESH

static fromPitch(pitch, numRings=25, armiObject=None, pointedEndUp=False, symmetry='')

Build a finite step-based 2-D hex grid from a hex pitch in cm.

Parameters:

• pitch (float) – Hex pitch (flat-to-flat) in cm

• numRings (int, optional) – The number of rings in the grid to pre-populate with locatator objects. Even if positions are not pre-populated, locators will be generated there on the fly.

• armiObject (ArmiObject, optional) – The object that this grid is anchored to (i.e. the reactor for a grid of assemblies)

• pointedEndUp (bool, optional) – Rotate the hexagons 30 degrees so that the pointed end faces up instead of the flat.

• symmetry (string, optional) – A string representation of the symmetry options for the grid.

Returns:

A functional hexagonal grid object.

Return type:

HexGrid

property pitch: float

Get the hex-pitch of a regular hexagonal array.

See also

armi.reactor.grids.HexGrid.fromPitch

static indicesToRingPos(i: int, j: int) → Tuple[int, int]

Convert spatialLocator indices to ring/position.

One benefit it has is that it never has negative numbers.

Notes

Ring, pos index system goes in counterclockwise hex rings.

getMinimumRings(n: int) → int

Return the minimum number of rings needed to fit n objects.

Notes

self is not used because hex grids always behave the same w.r.t. rings/positions.

getPositionsInRing(ring: int) → int

Return the number of positions within a ring.

getNeighboringCellIndices(i: int, j: int = 0, k: int = 0) → List[Tuple[int, int, int]]

Return the indices of the immediate neighbors of a mesh point in the plane.

Note that these neighbors are ordered counter-clockwise beginning from the 30 or 60 degree direction. Exact direction is dependent on pointedEndUp arg.

getLabel(indices)

Hex labels start at 1, and are ring/position based rather than i,j.

This difference is partially because ring/pos is easier to understand in hex geometry, and partially because it is used in some codes ARMI originally was focused on.

static getIndicesFromRingAndPos(ring: int, pos: int) → Tuple[int, int]

getRingPos(indices: Tuple[int, int, int]) → Tuple[int, int]

Get 1-based ring and position from normal indices.

See also

getIndicesFromRingAndPos

does the reverse

overlapsWhichSymmetryLine(indices: Tuple[int, int]) → Optional[int]

Return a list of which lines of symmetry this is on.

Parameters:

indices (tuple of [int, int]) – Indices for the requested object

Returns:

None if not line of symmetry goes through the object at the requested index. Otherwise, some grid constants like BOUNDARY_CENTER will be returned.

Return type:

None or int

Notes

• Only the 1/3 core view geometry is actually coded in here right now.

• Being “on” a symmetry line means the line goes through the middle of you.

getSymmetricEquivalents(indices: Tuple[int, int, int]) → List[Tuple[int, int]]

triangleCoords(indices: Tuple[int, int, int]) → ndarray

Return 6 coordinate pairs representing the centers of the 6 triangles in a hexagon centered here.

Ignores z-coordinate and only operates in 2D for now.

changePitch(newPitchCm: float)

Change the hex pitch.

locatorInDomain(locator, symmetryOverlap: Optional[bool] = False) → bool

isInFirstThird(locator, includeTopEdge=False) → bool

True if locator is in first third of hex grid.

generateSortedHexLocationList(nLocs: int)

Generate a list IndexLocations, sorted based on their distance from the center.

IndexLocation are taken from a full core.

Ties between locations with the same distance (e.g. A3001 and A3003) are broken by ring number then position number.

allPositionsInThird(ring, includeEdgeAssems=False)

Returns a list of all the positions in a ring (in the first third).

Parameters:

• ring (int) – The ring to check

• includeEdgeAssems (bool, optional) – If True, include repeated positions in odd ring numbers. Default: False

Notes

Rings start at 1, positions start at 1

Returns:

positions

Return type:

int

armiObject: Optional[ArmiObject]