2.2.23. averageDown

Purpose

Average each data block of size 'packing' into single values thus reducing the former grid to grid/packing.

Usage

```> averageDown options ASCII table(s)
```

Options

`-c` / `--coordinates` [ pos ]
column label of coordinates
`-p` / =--packing=[ 2 2 2 ]
size of packed group
=--shift=[ 0 0 0 ]
shift vector of packing stencil
`-g` / `--grid`
grid in x,y,z (optional)
`-s` / `--size`
size in x,y,z (optional)

Details

 Figure 1: Packing stencil concept exemplified in two dimensions.

For a periodic and regular grid stored in an ASCII table with x as fastest and z as slowest varying coordinate, calculate the average per block of given size. Grid resolution is reduced by the factor resulting from the chosen size of the packing stencil.

Figure 1 illustrates the concept in two dimensions with a 2 by 2 packing stencil. The original 4 by 4 grid is shown in light gray and might result from a 2 by 2 finite element mesh (black lines) with linear interpolation functions, thus containing four integration points each. During averaging, the stencil is moved across the whole grid in steps of 2 grid points along x and 2 grid points along y, i.e., in a non-overlapping fashion.

The (black) points of the resulting 4/2 by 4/2 = 2 by 2 grid fall into the center of the finite elements since a stencil shift of (0, 0) was employed in this example.

Using a stencil shift of either (-1,-1), (-1,1), (1,1), or (1,-1) in the example of Figure 1 would result in the new grid coinciding with the nodes of the finite elements and averaged from their four neighboring integration points (light gray; periodicity of the original data is always implied).

Topic attachments
I Attachment Action Size Date Who Comment
pdf averageDown.pdf manage 258 K 16 Feb 2012 - 10:04 PhilipEisenlohr packing stencil concept used in averageDown postprocessing script
png averageDown.png manage 9 K 16 Feb 2012 - 10:20 PhilipEisenlohr packing stencil concept used in averageDown postprocessing script
This topic: Documentation > Processing > PostProcessing > AverageDown
Topic revision: 09 Dec 2021, FranzRoters
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